Glutamic acid discovery

Trypsin inhibitors in cucumber were first found in a study by Walker-Simmons et /. " after wounding of leaves and treatment with proteinase inhibitor-inducing factor (PIIF). The amino acid sequence of two inhibitors isolated from Cucurhita maxima (winter squash) were determined by Wilusz et at The peptides named ITD I and ITD 111 each comprised a 29-residue sequence with six cysteine residues. The only difference between the two peptides is in position 9, which is lysine in ITD I and glutamic acid in ITD III. The reactive site is located at the peptide bond between Arg5 and Ile6. Owing to their discovery and distribution in Cucurbitaceae the inhibitor family has been named squash inhibitors. Since the initial discoveries many other members of the squash family have been found. 

The discovery of D-glutamic acid cyclotransferase was foreshadowed by the observations of Ratner (23) who fed rats D,L-glutamate labeled with 15N in the amino group and deuterium attached to the a- and / -... 

However, its a-carboxylate is often amidated or linked to an additional amino acid and in Microbacterium lacticum y-D-Glu is replaced by f/rreo-S-hydroxy-D-glutamic acid (3-Hyg). Most variation is found in position 3. If m-DAP (D,L-configuration) is incorporated, the L center is found in the pentapeptide chain and the D center in the side chain. Positions 4 and 5 (D-Ala-D-Ala) were for a long time thought to be invariant. However, the incidence of bacterial resistance to vancomycin-type glycopeptide antibiotics which recognize specifically the A-acyl-D-Ala-D-Ala terminus led to the discovery that these resistant strains contain altered substituents at position 5 as indicated in Fig. 16b [194,195,196]. 

The accepted mechanism for vitamin K is to function as a cofactor in the posttranslational synthesis of y ar-boxyl-glutamic acid (Glu) from glutamic acid residues. The discovery of Gla in 1974 - clarified the mechanism of vitamin K and led to the identification of additional vitamin K-dependent proteins. The only known function of vitamin K in mammals is to maintain adequate levels of vitamin K-dependent proteins involved in coagulation. The.se include prothrombin (factor II). factor VII (proconvertin), factor IX (autoprothrombin II). factor X (Stuart-Prower factor), and proteins C. S. and Z. Prothrombin and factors VII. IX. and X promote coagulation, while proteins C and S have anticoagulant activity. The function of protein Z is not known. 

In 1933, shortly following the discovery of phosphoserine (44), Schmidt, and Levene and Hill isolated from a casein hydrolyzate a dipeptide consisting of serine, glutamic acid, and phosphoric acid (38, 84). In 1941, Posternak and Pollaczek demonstrated the presence of a free a-amino group in the serine moiety of the molecule and assigned the following structure... 

Izumi and Akabori first invented MNi in 1963. They modified freshly prepared Raney nickel (W-1 type) with a mono-sodium salt of glutamic acid (Gul-MRNi). This catalyst gave a 15% e.d.a. for the hydrogenation of methyl acetoacetate (MAA) to methyl 3-hydroxybutanoate (MHB). It was sheer luck that MAA was employed as the substrate. Even today MAA is one of the best substrates, and it has long been employed as a standard. Immediately after the discovery by Izumi et al, Klabunovskii and coworkers started studies of this type of catalyst, and the groups led by Izumi and Klabunovskii carried out almost all the early research. ... 

The decarboxylation of glutamic acids to the neuronal transmitter y-aminobutyric acid (GABA) has been much studied, and since the original discovery that the reaction occurred with retention of configuration (247), the process has been used to prepare labeled samples of GABA (248-255). 

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