Amino acids first isolations

CgHjNOj, Mr 127.14, mp. 274°C (decomp.), [a] -288° (H2O) hydrochloride rap. 264°C, [a]g -90.1° (HjO). Non-proteinogenic amino acid first isolated from Rhodesian teak wood Baikiaea plurijuga (Faba-ceae) and later also from Caesalpinia tinctoria and red algae. B. inhibits the activity of glutamic acid as neurotransmitter. ... 

C7H,4Na04S, Mr 222.26, mp. 312 °C, [ajg +23.1 ° (1 m HCl). Widely distributed non-proteinogenic amino acid, first isolated from vetch (Astragalus pectinalis). 

L-Baikiain (1 3,6-tetrahydropyridine-a-carboxylic acid), a rare nonproteogenic amino acid first isolated... 

Cono toxins represent one of the more inspiring examples of marine toxins because of their outstanding biological activities in their habitat, in the sea, as well as their being drug leads.Ziconotide, (Prialt) a 25 amino acid peptide isolated from cones, became the first FDA approved drug for the treatment of neuropathic pain and severe chronic pain that do not respond to other forms of treatment. 

First, many of these antibiotics, after their discovery, characterization and evaluation, were not of sufficient practical importance and work on them was discontinued. Second, they have relatively complicated structures. Unlike the peptide hormones, which are composed of a limited number of natural amino acids found in proteins, many peptide antibiotics contain a large variety of components other than amino acids. Besides the frequently occurring amino acids not isolated from proteins Table 1.1), many other components, such as hydroxy acids, amino sugars, fatty acids, pyrimidine derivatives and so on, are present Table 1.2). They also often contain unusual peptide linkages, unknown in proteins. Furthermore, most of the peptide antibiotics are of cyclic nature and for this reason are resistant to enzymatic attack, which makes their structural elucidation in many instances more complicated. 

C4H,N02,Mr 101.1 l,mp. 229-231 °C. A non-proteinogenic amino acid first known as a synthetic product and later isolated from pears and apples. ACC is formed from methionine via 5-adenosylmethionine with the help of ACC synthase (EC 4.4.1.14) and cleaved by ACC oxidase to the multifunctional plant growth substance ethylene which plays key roles in various plant physiological processes such as ripening of fruit, aging, germination, and response to stress. 

Amino acids were isolated from natural sources, asparagine from plants, cystine from urinary stones in the first decade of the last century and became known later to be constituents of proteins. The peptide bond, however, as the fundamental feature of protein structure was recognized only in this century (Hofmeister 1902 E. Fischer 1906). Several more decades elapsed until sequence elucidation reached the point of practicality. The turning point was signaled by the determination of the structure of insulin (Sanger et al. 1953). The subsequent development of automated amino acid analysis (Spackman, Stein and Moore 1958) and automatic sequencing (Edman and Begg 1967)... 

Trihydroxybufosterocholenic acid (XII) (Fig. 7) (3a,7a, 12a-trihydroxy-24-methyl-j22-coprostanic acid) is an example of a 28-carbon-atom bile acid first isolated from the bile of the toad, Bufo vulgaris, by Shimizu and Oda (51). All known C27 and Cga bile acids occur in nature as conjugates with the amino acid, taurine. There are several other acids in this group, which will be described in detail in subsequent chapters. 

CgHiiNO. M.p. 282 C (decomp.). The naturally occurring substance is laevorotatory. It is an amino-acid isolated from various plant sources, but not found in the animal body. It is formed from tyrosine as the first stage in the oxidation of tyrosine to melanin. It is used in the treatment of Parkinson s disease. 

At the time of the discovery of Met-enkephalin, its sequence was observed to be identical to that of residues 61—65 contained in the C-fragment of the pituitary hormone p-Hpotropin [12584-99-5] (p-LPH) (see Hormones), first isolated in 1964 (11). In 1976, the isolation of a larger peptide fragment, P-endorphin [60617-12-1] that also displayed opiate-like activity was reported (12). This peptide s 31-amino-acid sequence comprised residues 61—91 of P-LPH. Subsequentiy, another potent opioid peptide, dynorphin [72957-38-17, was isolated from pituitary (13). The first five amino acids (qv) of this 17-amino-acid peptide are identical to the Leu-enkephalin sequence (see Table 1). 

Riboflavin-5 -Adenosine Diphosphate. Riboflavin-5 -adenosine diphosphate [146-14-5] (flavin—adenine dinucleotide, FAD), C27H33N9O15P2 (2), mol wt 785.56, was first isolated in 1938 from the D-amino acid oxidase as its prosthetic group (95), where it was postulated to be... 

Riboflavin was first isolated from whey in 1879 by Blyth, and the structure was determined by Kuhn and coworkers in 1933. For the structure determination, this group isolated 30 mg of pure riboflavin from the whites of about 10,000 eggs. The discovery of the actions of riboflavin in biological systems arose from the work of Otto Warburg in Germany and Hugo Theorell in Sweden, both of whom identified yellow substances bound to a yeast enzyme involved in the oxidation of pyridine nucleotides. Theorell showed that riboflavin 5 -phosphate was the source of the yellow color in this old yellow enzyme. By 1938, Warburg had identified FAD, the second common form of riboflavin, as the coenzyme in D-amino acid oxidase, another yellow protein. Riboflavin deficiencies are not at all common. Humans require only about 2 mg per day, and the vitamin is prevalent in many foods. This vitamin... 

The isotope dilution principle, first employed by Hevesy and Hobbie (133) in 1932 for the determination of lead in ores, was applied by Schoenheimer et al. (241) to the determination of amino acids. [Shemin and Foster (248) have reviewed this topic.] An N15-amino acid derivative was added to a protein hydrolyzate, a sample of the amino acid to be determined was isolated and purified, the excess N15 in this product was estimated with the mass spectrograph, and the grams of amino acid originally present were calculated from Equation 2. 

Of the twenty amino acids that are normally found in proteins, only two contain sulfur, cysteine and methionine. Cysteine has long been recognized as being easily oxidized and this oxidation is associated with the loss of biological activity of many proteins. In recent years, it has been shown that methionine also shares these characteristics. Methionine was first isolated by Mueller19 and was one of the last amino acids discovered. Its structure was later proven to be y-methylthio-a-aminobutyric acid by Barger and Coyne20 who named the amino acid methionine as a contraction for its chemical name. 

The first reported method for the direct phosphonomethylation of amino acids used phosphorous acid and formaldehyde (7). Typically, aqueous solutions of the amino acid, phosphorous acid, and concentrated (coned) hydrochloric acid were heated to reflux with excess aqueous formaldehyde or paraformaldehyde. The reaction proceeded equally well with either primary or secondary amines. However, with primary amines such as glycine, the yield of glyphosate was usually quite low, even at reduced temperature, and 1 1 1 stoichiometry. The resulting glyphosate acid (GLYH3) reacted faster than glycine, so the bis-phosphonomethyl adduct 2 always predominated. With excess phosphorous acid and formaldehyde, good isolated yields of this 2 1 adduct 2 have been obtained (8). 

---