Glu decarboxylase

D-glutamic acid L-glutamic acid Glu decarboxylase + Glu racemase iMctohac. brevis 207... 

Glu decarboxylase His decarboxylase Aromatic AA decarboxylase Glu decarboxylase His decarboxylase Ornithine decarboxylase Arg decarboxylase Lw decarbonlase... 

Tissues of the mammalian central nervous system contain a pyridoxal phosphate-dependent glutamate decarboxylase that catalyzes conversion of Glu to y-aminobutyrate (GABA), an inhibitory synaptic transmitter. GABA is degraded by trans-imination with a-oxoglutarate as the acceptor to yield succinic semialdehyde, which then is oxidized to succinate by an NAD-linked dehydrogenase. 

FIGURE 8—16. Gamma-aminobutyric acid (GABA) is produced by synthesis from the precursor amino acid glutamate by the enzyme glutamic acid decarboxylase (Glu-AD). 

Figure 2.5 Logarithmic scale comparison of k,d and kuncat (= (rnon) for some representative reactions at 25 °C. The length of each vertical bar represents the rate enhancement. (Wolfenden, 2001). ADC arginine decarboxylase ODC orotidine 5 -phosphate decarboxylase STN staphylococcal nuclease GLU sweet potato /3-amylase FUM fumarase MAN mandelate racemase PEP carboxypeptodase B CDA E. coli cytidine deaminase KSI ketosteroid isomerase CMU chorismate mutase CAN carbonic anhydrase.

GLP-1, glucagon like peptide-1 Glu, glutamate, glutamic acid GluDG, glutamate decarboxylase Glu-R, glutamate ionotropic receptor Gly, glycine... 

Similar results were obtained in our studies on the thiamin-dependent indole-pyruvate decarboxylase, where protonation and deprotonation reactions are also catalyzed by a Glu-cofactor proton shuttle and a His-Asp-Glu relay (Schiitz et al., 2005). 

The pH dependence of the kinetics of histidine decarboxylase (127) demonstrates that the histidine is zwitterionic when it binds to the enzyme. The extra proton on nitrogen must, of course, be removed before the Schiff base is formed. The carboxylate of Glu-197 at the active site may accept this proton. In turn, this same group may then be responsible for proton donation to the Schiff base following decarboxylation. This is consistent with the occurrence of retention of configuration in the overall replacement of-C02 by -H (128) and with studies of enzymes altered at Glu-197 (129). When Glu-197 is replaced by Asp, the protonation that follows decarboxylation occasionally occurs on the pyruvate side, thus giving rise to decarboxylation-dependent transamination (129). 

C7H,4N203, Mr 174.20, mp. 217-218 C (decomp.), [a]Q 4-8.7° (H2O). A component of leaves of the tea plant (Camellia sinensis), also occurring in the finit bodies of the fungus Xerocomus badius. Biosynthesis From Glu, ethylamine, and ATP. Ethyl-amine in tea shoots probably originates from L-Ala by the action of alanine decarboxylase In green tea T. 

In the same scheme, a representation of the action of tyrosine transaminase (EC 2.6.1.5) acting on tyrosine (Tyr, Y) is shown. This enzyme utilizes pyridoxal phosphate to remove toe amino group from tyrosine (Tyr, Y) and transfer it to a-ketoglutarate (2-oxoglutarate) with formation of glutamate (Glu, E) from the latter and 4-hydroxyphenylpyruvate from the former. Then, 4-hydroxyphenylpyruvate decarboxylase (EC 4.1.1.80), which appears to require thiamine diphosphate and... 

Some proteins are subject to the C-terminal rule which predicts that proteins having a C-terminal stretch comprised predominantly of a PEST (Pro, Glu, Ser, and Thr) sequence motif are rapidly degraded (41). For example, ornithine decarboxylase containing the C-terminal PEST sequence has a half-life at least four times shorter than the same protein without the PEST motif (42). The PEST rule is subject to the polarity of the terminal residues nonpolar amino acids are destabilizing when placed at the five amino acid positions of the C terminus, whereas charged and polar residues are stabilizing (43). 

Figure 14.2. Example of some metabolic pathways adopted by Lactobacillus plantarum during fermentation of vegetable and fruit juices. He, isoleucine Leu, leucine Val, valine His, histidine Glu, glutamic acid BcAT, branched-chain aminotransferase KDC, a-keto acid decarboxylase ADH, alcohol dehydrogenase MLE, malol-actlc enzyme HDC, histidine decarboxylase (Adapted from Filannino etal. 2014)...

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