Bacteria acid hydrolases

D-Amino acid oxidase occurs in peroxisomes containing other enzymes that produce H2O2 (e.g., L-a-hydroxy acid oxidase, citrate dehydrogenase, and L-amino acid oxidase) and catalase and peroxidase, which destroy H2O2. In leukocytes, killing of bacteria involves hydrolases of lysosomes and production of H2O2 by NADPH oxidase (Chapter 15). Conversion of D-amino acids to the corresponding a-keto acids removes the asymmetry at the a-carbon atom. The keto acids may be aminated to L-amino acids. By this conversion from D- to L-amino acids, the body utilizes D-amino acids derived from the diet ... 

The ability to hydrolyze the peptide bond in conjugated bile acids (Fig. 1) is widely distributed among intestinal bacteria. Conjugated bile acid hydrolase (CBH) (EC 3.5) activity has been detected in members of the genera Bacteroides, Bifidobacterium, Fusobacterium, Clostridium, Lactobacillus, Peptostreptococcus and Streptococcus [13-17]. However, there is considerable variation in occurrence of this enzymatic activity among species and strains. 

Characteristics of conjugated bile acid hydrolase from intestinal bacteria ... 

Lysosomes and peroxisomes Lysosomes contain digestive enzymes (acid hydrolases). They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. Peroxisomes have enzymes that rid the cell of toxic peroxides. 

Poly(L-malate) [poly(malic acid) (PMA)], is a water-soluble polyanion produced by slime molds and some yeasts such as Physarum polycephalum or Aureobasidium pullulans, respectively. Its function and metabolism has been studied during the last few years [122-125]. Recently, several PMA-degrad-ing bacteria have been isolated, and a cytoplasmic membrane-bound PMA hydrolase was purified from Comamonas acidovans strain 7789 [126] that... 

Alternative potential strategies for reduction of mucosal secondary bile acid exposure are to target deconjugation of glycine/taurine bile salts by bacterial bile salt hydrolases and/or bacterial 7-dehydroxylation of primary bile acids to secondary bile acids. Sequestration of bile acids in the intestinal lumen using probiotic bacteria has also been proposed as an area for future research. ... 

Oterholm, A., Ordal, Z.J., Witter, L.D. 1968. Glycerol ester hydrolase activity of lactic acid bacteria. Appl. Microbiol. 16, 524-527. 

Around one-quarter of the bile acid conjugates reaching the ileum have the amino acid moiety removed by the action of bacterial enzymes. A decon-jugating enzyme, choloylglycine hydrolase (EC 3.5.1.24) has been isolated from clostridial bacteria (Nl) and is used in methods for the analysis of bile acids. The majority of deconjugated bile acids are reabsorbed and return to the liver, where they are efficiently reconjugated with glycine or taurine (V7). 

FAAH is a membrane-bound serine hydrolase, that shows its maximal activity at pH 9 (Cravatt et al., 1996). This enzyme belongs to a protein family called amidase signature (AS) (Chebrou et al., 1996), whose members share a common, conserved amino acid sequence comprising 130 residues, the so-called amidase-signature sequence . The AS family of enzymes is mainly represented among bacteria and fungi, and FAAH was, until recently, the only known representative of this class of proteins in mammals. 

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