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53-421: Histidine was first isolated by Albrecht Kossel and Sven Gustaf Hedin in 1896. The name stems from its discovery in tissue, from ἱστός histós "tissue". It is also a precursor to histamine , a vital inflammatory agent in immune responses. The acyl radical is histidyl . The conjugate acid (protonated form) of the imidazole side chain in histidine has a p K a of approximately 6.0. Thus, below

106-418: A belly that is paler greenish olive. The adult color pattern develops within 3 to 4 months. In the wild A. squamigeras begin reproducing once they reach sexual maturity at 42 months for females, and at 24 months for males respectively. Reproduction takes place once annually, most often during the wet season. A. squamigera is viviparous, and a single successful pairing can produce up to 19 neonates, although

159-548: A few months. Bites from A. squamigera have resulted in at least one report of severe hematological complications as well as two deaths. Although no specific antivenom is made for the genus Atheris , antivenom for the genus Echis has been shown to be partially effective in neutralizing Atheris venom. A number of subspecies of A. squamigera may be encountered in literature. These include: Furthermore, specimens from Dimonika and Menengue in Congo are sometimes treated as

212-423: A histidine proton shuttle , histidine is used to quickly shuttle protons. It can do this by abstracting a proton with its basic nitrogen to make a positively charged intermediate and then use another molecule, a buffer, to extract the proton from its acidic nitrogen. In carbonic anhydrases , a histidine proton shuttle is utilized to rapidly shuttle protons away from a zinc -bound water molecule to quickly regenerate

265-463: A pH of 6, the imidazole ring is mostly protonated (as described by the Henderson–Hasselbalch equation ). The resulting imidazolium ring bears two NH bonds and has a positive charge. The positive charge is equally distributed between both nitrogens and can be represented with two equally important resonance structures . Sometimes, the symbol Hip is used for this protonated form instead of

318-470: A very high level of humidity to breed. In one case, males and females were kept separate from January to the end of November. Two females became gravid (with one observed mating). Each produced eight young: a smaller percentage were yellow (possible recessive gene), most being green. In each brood, there was also one nonviable green specimen. Some of the neonates fed readily on frogs , while the others had to be force-fed pinkie mice . All fed independently after

371-469: A very large gape. The head is thickly covered with keeled, imbricate scales. The rostral scale is not visible from above. A very small scale just above the rostral is flanked by very large scales on either side. The nostrils are lateral. The eye and the nasal are separated by 2 scales. Across the top of the head, there are 7 to 9 interorbital scales . There are 10 to 18 circumorbital scales . There are 2 (rarely 1 or more than 2) rows of scales that separate

424-416: Is aromatic at all pH values. Under certain conditions, all three ion-forming groups of histidine can be charged forming the histidinium cation. The acid-base properties of the imidazole side chain are relevant to the catalytic mechanism of many enzymes . In catalytic triads , the basic nitrogen of histidine abstracts a proton from serine , threonine , or cysteine to activate it as a nucleophile . In

477-408: Is a venomous viper species endemic to west and central Africa . No subspecies are currently recognized. Atheris squamigera grows to an average total length (body + tail) of 46 to 60 cm (18 to 24 in), with a maximum total length that sometimes exceeds 78 cm (31 in). Females are usually larger than males. The head is broad and flat, distinct from the neck. The mouth has

530-415: Is an essential amino acid that is not synthesized de novo in humans. Humans and other animals must ingest histidine or histidine-containing proteins. The biosynthesis of histidine has been widely studied in prokaryotes such as E. coli . Histidine synthesis in E. coli involves eight gene products (His1, 2, 3, 4, 5, 6, 7, and 8) and it occurs in ten steps. This is possible because a single gene product has

583-461: Is converted to l -histidine. The histidine biosynthesis pathway has been studied in the fungus Neurospora crassa , and a gene ( His-3 ) encoding a multienzyme complex was found that was similar to the His4 gene of the bacterium E. coli . A genetic study of N. crassa histidine mutants indicated that the individual activities of the multienzyme complex occur in discrete, contiguous sections of

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636-552: Is first converted to urocanate by histidase. Then, urocanase converts urocanate to 4-imidazolone-5-propionate. Imidazolonepropionase catalyzes the reaction to form formiminoglutamate (FIGLU) from 4-imidazolone-5-propionate. The formimino group is transferred to tetrahydrofolate , and the remaining five carbons form glutamate. Overall, these reactions result in the formation of glutamate and ammonia. Glutamate can then be deaminated by glutamate dehydrogenase or transaminated to form α-ketoglutarate. The Food and Nutrition Board (FNB) of

689-463: Is for his work in this respect that the Nobel Prize has been awarded to him this year. Albrecht Kossel is considered one of the great scientists of biochemistry and genetics. By isolating and defining nucleic acid and the nucleobases , he provided the necessary precursors that led to the double-helix model of DNA , devised by James D. Watson and Francis Crick in 1953. " … his elucidation of

742-632: Is given as "Near the river Gaboon, Guinea" [Gabon]. Atheris squamigera is the most well distributed species of the Atheris genus. Scientists believe that the current pattern of dispersal is of the Atheris species, including that of the A. squamigera may have been influenced by a combination of past climatic events, geological activities, the shifting of tectonic plates over millions of years, as well as stochastic dispersal. Atheris squamigera inhabits mostly rainforest , preferring relatively low and thick flowering bushes . Atheris squamigera requires

795-438: Is regulated through feedback inhibition meaning that it is inhibited in the presence of the product, histidine. Histidine is one of the amino acids that can be converted to intermediates of the tricarboxylic acid (TCA) cycle (also known as the citric acid cycle). Histidine, along with other amino acids such as proline and arginine, takes part in deamination, a process in which its amino group is removed. In prokaryotes , histidine

848-436: Is the axial base attached to Fe in myoglobin and hemoglobin. Poly-histidine tags (of six or more consecutive H residues) are utilized for protein purification by binding to columns with nickel or cobalt, with micromolar affinity. Natural poly-histidine peptides, found in the venom of the viper Atheris squamigera have been shown to bind Zn(2+), Ni(2+) and Cu(2+) and affect the function of venom metalloproteases. l -Histidine

901-472: Is the same in some populations, but variable in others. The dorsal color varies from sage green or light green to green, dark green, bluish, olive or dark olive brown. Rare specimens may be found that are yellow, reddish or slate gray. The scales have light-colored keels and sometimes yellow tips that form a series of 30 or more light crossbands or chevrons. On the tail, there are 10 to 19 chevrons: not always clearly defined, but usually present. The ventral edge of

954-549: The His-3 genetic map , suggesting that the different activities of the multienzyme complex are encoded separately from each other. However, mutants were also found that lacked all three activities simultaneously, suggesting that some mutations cause loss of function of the complex as a whole. Just like animals and microorganisms, plants need histidine for their growth and development. Microorganisms and plants are similar in that they can synthesize histidine. Both synthesize histidine from

1007-575: The Sommerfeld–Kossel displacement law , and other achievements. Albrecht Kossel was apparently not greatly interested in politics, but in 1914 he did not sign the propaganda Pronunciamento of German professors at the start of the war. He suffered under the lies which filled the world in war time. In 1917 Kossel was summoned by the government to pronounce that the allotted food provisions were sufficient. He refused this demand, would never declare untruths as truths Through his marriage to Luise, Kossel

1060-725: The U.S. Institute of Medicine set Recommended Dietary Allowances (RDAs) for essential amino acids in 2002. For histidine, for adults 19 years and older, 14 mg/kg body weight/day. Supplemental histidine is being investigated for use in a variety of different conditions, including neurological disorders, atopic dermatitis, metabolic syndrome, diabetes, uraemic anaemia, ulcers, inflammatory bowel diseases, malignancies, and muscle performance during strenuous exercise. Albrecht Kossel Ludwig Karl Martin Leonhard Albrecht Kossel ( German pronunciation: [ˈalbʁɛçt ˈkɔsl̩] ; 16 September 1853 – 5 July 1927)

1113-454: The University of California at Berkeley , who was also his wife's cousin. He also visited and delivered lectures at several other universities, including the University of Chicago . On the occasion of his visit to New York City, Kossel was interviewed by a reporter from The New York Times . Kossel's English was reportedly very good, and his self-effacing modesty is voluminously mentioned in

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1166-561: The cell nucleus , and for his work in isolating and describing nucleic acids . The award was presented on 10 December 1910. In the autumn of 1911, Kossel was invited to the United States to deliver the Herter Lecture at Johns Hopkins . Traveling with his wife Luise and daughter Gertrude, he took the opportunity to travel and to visit acquaintances, one of which was Eugene W. Hilgard , professor emeritus of agricultural chemistry at

1219-507: The polypeptide nature of the protein molecule. The processes of life are like a drama, and I am studying the actors, not the plot. There are many actors, and it is their characters which make this drama. I seek to understand their habits, their peculiarities. Kossel was awarded the Nobel Prize in Physiology or Medicine in 1910 for his research in cell biology , the chemical composition of

1272-687: The Eleventh Physiological Congress in Edinburgh , Scotland. When he appeared before the assembled scientists, they gave him an ovation that lasted several minutes. At the congress, he was conferred an honorary degree by the University of Edinburgh . In 1924, Kossel became professor emeritus , but continued to lecture at Heidelberg University . In April 1927, he attended the Lister Centenary Celebration held in England. During

1325-658: The Gymnasium at Rostock, where he evidenced substantial interest in chemistry and botany. In 1872, Kossel attended the University of Strassburg to study medicine. He studied under Felix Hoppe-Seyler , who was head of the department of biochemistry, the only such institution in Germany at the time. He attended lectures by Anton de Bary , Waldeyer , August Kundt , and Baeyer . He completed his studies at University of Rostock , and passed his German medical license exam in 1877. After completing his university studies, Kossel returned to

1378-458: The His6 gene product. His7 splits phosphoribulosylformimino-AICAR-P to form d -erythro-imidazole-glycerol-phosphate. After, His3 forms imidazole acetol-phosphate releasing water. His5 then makes l -histidinol-phosphate, which is then hydrolyzed by His2 making histidinol . His4 catalyzes the oxidation of l -histidinol to form l -histidinal, an amino aldehyde. In the last step, l -histidinal

1431-529: The University of Strassburg as research assistant to Felix Hoppe-Seyler. At the time, Hoppe-Seyler was intensely interested in research concerning an acidic substance that had first been chemically isolated from pus cells by one of his former students, Friedrich Miescher , in 1869. Unlike protein, the substance contained considerable amounts of phosphorus , but with its high acidity, it was unlike any cellular substance that had yet been observed. Kossel showed that

1484-432: The ability to catalyze more than one reaction. For example, as shown in the pathway, His4 catalyzes 4 different steps in the pathway. Histidine is synthesized from phosphoribosyl pyrophosphate (PRPP), which is made from ribose-5-phosphate by ribose-phosphate diphosphokinase in the pentose phosphate pathway . The first reaction of histidine biosynthesis is the condensation of PRPP and adenosine triphosphate (ATP) by

1537-531: The active form of the enzyme. In helices E and F of hemoglobin , histidine influences binding of dioxygen as well as carbon monoxide . This interaction enhances the affinity of Fe(II) for O2 but destabilizes the binding of CO, which binds only 200 times stronger in hemoglobin, compared to 20,000 times stronger in free heme . The tautomerism and acid-base properties of the imidazole side chain has been characterized by N NMR spectroscopy. The two N chemical shifts are similar (about 200 ppm, relative to nitric acid on

1590-488: The average is 7–9. The female A. squamigera carries her young internally during a gestation period of two months. Following birth, the neonates are abandoned by the mother as they are born venomous and entirely self sufficient. The diet of Atheris squamigera consists primarily of small mammals, although cases of cannibalism within the species have been documented. A. squamigera is a nocturnal hunter and its coloring allows it to blend in with its environment and ambush

1643-409: The biochemical intermediate phosphoribosyl pyrophosphate. In general, the histidine biosynthesis is very similar in plants and microorganisms. This pathway requires energy in order to occur therefore, the presence of ATP activates the first enzyme of the pathway, ATP-phosphoribosyl transferase (shown as His1 in the image on the right). ATP-phosphoribosyl transferase is the rate determining enzyme, which

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1696-448: The chemical nature of some building blocks that make up nucleic acids and chromatine has secured immortality for this exeedingly modest and almost shy man." The Albrecht Kossel Institute for Neuroregeneration at the University of Rostock is named in his honor. Atheris squamigera Atheris squamigera (common names: green bush viper , variable bush viper , leaf viper , Hallowell's green tree viper , and others )

1749-470: The composition of protein , and his research predicted the discovery of the polypeptide nature of the protein molecule. The Albrecht Kossel Institute for Neuroregeneration at the University of Rostock is named in his honor. Kossel was born in Rostock , Germany as the son of the merchant and Prussian consul Albrecht Karl Ludwig Enoch Kossel and his wife Clara Jeppe Kossel. As a youth, Kossel attended

1802-519: The dorsum has light spots in pairs. An interstitial black color is visible only when the skin is stretched. The belly is yellow or dull to pale olive; it may be uniform in color, or heavily mottled with blackish spots. The throat is sometimes yellow. The tail has a conspicuous ivory white tip, 7 to 12 mm long, extending back over 10 subcaudals. Neonates have a dark, olive coloration with wavy bars, paler olive or yellowish olive with fine dark olive margins, bars at 5 mm (0.20 in) intervals, and

1855-407: The enzyme ATP-phosphoribosyl transferase . ATP-phosphoribosyl transferase is indicated by His1 in the image. His4 gene product then hydrolyzes the product of the condensation, phosphoribosyl-ATP, producing phosphoribosyl-AMP (PRAMP), which is an irreversible step. His4 then catalyzes the formation of phosphoribosylformiminoAICAR-phosphate, which is then converted to phosphoribulosylformimino-AICAR-P by

1908-479: The eyes from the labials . There are 9 to 12 supralabials and 9 to 12 sublabials . Of the latter, the anterior 2 or 3 touch the chin shields, of which there is only one small pair. The gular scales are keeled. Midbody there are 15 to 23 rows of dorsal scales , 11 to 17 posteriorly. There are 152 to 175 ventral scales and 45 to 67 undivided subcaudals . It is possible that there is a variation in morphometric characters related to habitat: The coloration

1961-541: The formation of DNA and RNA , the genetic material found in all living cells. Kossel was an important influence on and collaborator with other important researchers in biochemistry, including Henry Drysdale Dakin , Friedrich Miescher , Edwin B. Hart , and his professor and mentor, Felix Hoppe-Seyler . Kossel was editor of the Zeitschrift für Physiologische Chemie (Journal of Physiological Chemistry) from 1895 until his death. Kossel also conducted important research into

2014-462: The last years of Kossel's life, he conducted important research into the composition of the protein types protamines and histones , and introduced flavianic acid for the quantitative separation of arginine, histidine and lysine in proteins. A monograph describing this work was published shortly after his death. Kossel contributed to early issues of the Zeitschrift für Physiologische Chemie (Journal of Physiological Chemistry). This publication

2067-530: The quantitative separation of the "hexone bases" (the alpha-amino acids arginine , histidine , and lysine ). He was also the first to isolate theophylline , a therapeutic drug found naturally in tea and cocoa beans. In 1901, Kossel was named to a similar post at Heidelberg University , and became director of the Heidelberg Institute for Protein Investigation. His research predicted the discovery of

2120-437: The reporter's account. His Herter lecture at Johns Hopkins was titled, "The Proteins". This was the only time Kossel ever visited the United States. With his distinguished English pupil Henry Drysdale Dakin , Kossel investigated arginase , the ferment which hydrolyses arginine into urea and ornithine . Later, he discovered agmatine in herring roe and devised a method for preparing it. Another of Kossel's students

2173-414: The second-order paramagnetic effect, which involves a symmetry-allowed interaction between the nitrogen lone pair and the excited π* states of the aromatic ring . At pH > 9, the chemical shifts of N1 and N3 are approximately 185 and 170 ppm. Histidine forms complexes with many metal ions. The imidazole sidechain of the histidine residue commonly serves as a ligand in metalloproteins . One example

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2226-475: The sigma scale, on which increased shielding corresponds to increased chemical shift ). NMR spectral measurements shows that the chemical shift of N1-H drops slightly, whereas the chemical shift of N3-H drops considerably (about 190 vs. 145 ppm). This change indicates that the N1-H tautomer is preferred, possibly due to hydrogen bonding to the neighboring ammonium . The shielding at N3 is substantially reduced due to

2279-608: The small prey it feeds on. It is equipped with two front hollow fangs through which it injects its prey with hemotoxic venom rendering it defenseless. Common names for A. squamigera include green bush viper, variable bush viper, leaf viper, common bush viper, bush viper, tree viper, Hallowell's green tree viper. and Yété in Mongo . Atheris squamigera is found in the forest habitats of West and central Africa : from Ghana eastward to western Kenya and Tanzania , south to northern Angola and Bioko Island . The type locality

2332-607: The substance, called "nuclein", consisted of a protein component and a non-protein component. Kossel further isolated and described the non-protein component. This substance has become known as nucleic acid , which contains the genetic information found in all living cells. In 1883, Kossel left Strassburg to become Director of the Chemistry Division of the Physiological Institute at the University of Berlin . In this post, he succeeded Eugen Baumann and worked under

2385-452: The supervision of Emil du Bois-Reymond . Kossel continued his previous work on the nucleic acids. During the period 1885 to 1901, he was able to isolate and name its five constituent organic compounds : adenine , cytosine , guanine , thymine , and uracil . These compounds are now known collectively as nucleobases , and they provide the molecular structure necessary in the formation of stable DNA and RNA molecules. In 1895, Kossel

2438-559: The usual His. Above pH 6, one of the two protons is lost. The remaining proton of the imidazole ring can reside on either nitrogen, giving rise to what are known as the N3-H or N1-H tautomers . The N3-H tautomer is shown in the figure above. In the N1-H tautomer, the NH is nearer the backbone. These neutral tautomers, also referred to as Nε and Nδ, are sometimes referred to with symbols Hie and Hid , respectively. The imidazole/imidazolium ring of histidine

2491-433: The view that its smallest independent units morphologically speaking – the cells – also to a certain degree lead an independent life and are the real seats of the vital processes. The cells therefore attract special attention in biological research, and studies which widen our knowledge of the cells to any important extent deserve to be given prominence. Prof. Kossel has chosen to devote himself to this field of research, and it

2544-401: Was American biochemist Edwin B. Hart , who would later return to the United States to participate in the " Single-grain experiment " (1907–1911) and be part of research teams that would determine the nutritive causes of anemia and goiter . Another was Otto Folin , an American chemist who discovered Phosphocreatine . In 1923, Kossel was honored by being named Germany's representative to

2597-476: Was a German biochemist and pioneer in the study of genetics . He was awarded the Nobel Prize for Physiology or Medicine in 1910 for his work in determining the chemical composition of nucleic acids , the genetic substance of biological cells . Kossel isolated and described the five organic compounds that are present in nucleic acid : adenine , cytosine , guanine , thymine , and uracil . These compounds were later shown to be nucleobases , and are key in

2650-487: Was also a noted philologist of his day. The couple had three children, two of whom survived to maturity: Walther, born in 1888, and daughter Gertrude, born in 1889. Son Walther Kossel (1888–1956) became a prominent physicist and was professor of theoretical physics and director of the Physics Institute at the University of Tübingen . He is known for his theory of the chemical bond ( ionic bond / octet rule ),

2703-570: Was founded by his professor and mentor, Felix Hoppe-Seyler , in 1877, the same year that Kossel started work as his research assistant. After Hoppe-Seyler's death in 1895, Kossel took over editorship of the Zeitschrift and continued in that role until his own death in 1927. In 1886, Kossel married Luise Holtzman, daughter of Adolf Holtzmann . Holtzmann was Professor at the University of Heidelberg , lecturing in German literature as well as Sanskrit . He

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2756-408: Was professor of physiology as well as director of the Physiological Institute at the University of Marburg . Around this time, he began investigations into the chemical composition of proteins , the alterations in proteins during transformation into peptone , the peptide components of cells, and other investigations. In 1896, Kossel discovered histidine , then worked out the classical method for

2809-472: Was related to several prominent Americans, including soil science pioneer Eugene W. Hilgard , journalist and financier Henry Villard , and abolitionist William Lloyd Garrison . Luise Kossel died in 1913 of acute pancreatitis . Kossel died quietly on 5 July 1927, after a recurring attack of angina pectoris . He is buried in Heidelberg , Germany. The study of the living organism has more and more led to

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