Factors influencing bacterial deamination

Abstract

The deamination activity of Bact. coli towards l-aspartic acid varied with (a) conditions of growth and (b) age of the culture. The latter was shown to be due to an alteration in the chemical constitution of the growth medium consequent upon the metabolic activity of the cells. Washed suspensions lost activity on standing; rate of loss being proportional to dilution. Lost activity was regained by addition of boiled bacteria (I) or formate to the suspension. Recovery due to (I) resembled coenzyme effect. The coenzyme could be replaced by adenylic acid and breakdown products; most active being adenosine. Addition of adenosine to bacterial suspension resulted in greatly increased rate of deamination aerobically or an-aerobically. Cell-free juice obtained from crushed coli de-aminated l-aspartic acid and fractionated with (NH4)2SO4 gave separation of 2 enzymes: aspartase I unaffected by toluene or adenosine and aspartase II completely inhibited by toluene and requiring a coenzyme replaceable by adenosine. The distribution of aspartase I II was detd. in strains of Bact. coli: II predominating. Formate acti- vated II aerobically, apparently by reducing the amt. of adenosine required for activation. Aspartase II-fraction of juice contained fumarase and produced NH3, fumaric and malic acids from l-aspartic acid.