Bacterial type, amino acid

In terms of amino acids bacterial protein is similar to fish protein. The yeast s protein is almost identical to soya protein fungal protein is lower than yeast protein. In addition, SCP is deficient in amino acids with a sulphur bridge, such as cystine, cysteine and methionine. SCP as a food may require supplements of cysteine and methionine whereas they have high levels of lysine vitamins and other amino acids. The vitamins of microorganisms are primarily of the B type. Vitamin B12 occurs mostly hi bacteria, whereas algae are usually rich in vitamin A. The most common vitamins in SCP are thiamine, riboflavin, niacin, pyridoxine, pantothenic acid, choline, folic acid, inositol, biotin, B12 and P-aminobenzoic acid. Table 14.4 shows the essential amino acid analysis of SCP compared with several sources of protein. 

In eukaryotes there is also evidence that Met(O) is actively transported. It has been reported that Met(O) is transported into purified rabbit intestinal and renal brush border membrane vesicles by a Met-dependent mechanism and accumulates inside the vesicles against a concentration gradient102. In both types of vesicles the rate of transport is increased with increasing concentrations of Na+ in the incubation medium. The effect of the Na+ is to increase the affinity of Met(O) for the carrier. Similar to that found in the bacterial system, the presence of Met and other amino acids in the incubation medium decreased the transport of Met(O). These results suggest that Met(O) is not transported by a unique carrier. 

The PelX protein contains 749 amino-acids including an amino-terminal signal sequence of 26 amino-adds. The celliilar localisation of the enzyme has not been rigorously determined. In E. chrysanthemi CUCPB1237, the exo-pectate lyase activity was cell-bound (14). The presence of this type of enzyme in the bacterial periplasm appeared normal since it acts better on oligomers produced by endo-pectate lyases than on long polymeric substrates (15). 

This approach is not restricted to bacterial or viral cells. Mammalian cells under highly proliferating conditions can be cultured at increasing exposure to a compound in attempts to create resistant mutants. Alternatively, one can sometimes use a structural biology approach to predict amino acid changes that would abrogate inhibitor affinity from study of enzyme-inhibitor complex crystal structures. If the recombinant mutant enzyme displays the diminished inhibitor potency expected, one can then devise ways of expressing the mutant enzyme in a cell type of interest and look to see if the cellular phenotype is likewise abolished by the mutation. 

The hardness of only one type of protein crystal has been found in the literature. It is for lysozyme. This is an enzyme found in egg whites and tears. It destroys bacterial membranes. It is relatively small for a protein molecule, consisting of a chain of 129 amino acids folded into a globule with the volume = 30,000 A3. Its crystals are aggregates of these globular molecules held together by London forces (Stryer, 1988). 

A group of enzymes which may be employed in the measurement of L amino acids are the L-amino acid decarboxylases (EC 4.1.1) of bacterial origin, many of which are substrate specific. They catalyse reactions of the type ... 

Studies on the bacterial type 1 protein azurin have been extensive. Ten different azurin amino-acid sequences have been determined with 47 out of 129 residues (Mf 14,(XX)) conserved. Reduction potentials are in the range 280 339 mV at... 

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