The mechanism of action of fructose diphosphate aldolase

The Mechanism of Action of Aldolases

“…The mechanism shown in figure 1 is consistent with the early theoretical considerations which led to the postulate that the aldolasetype reaction is catalyzed both by a Schiff base (49)(50)(51) and by a base catalyst (2,(18)(19)(20)(21). It is interesting to compare this mechanism with the results reported by Westheimer and Cohen (50), who found that an aldol cleavage was catalyzed by an amine (thought to form a Schiff base complex) together with hydroxide ion.…”

“…The Schiff base-forming aldolases, as mentioned before, do not contain significant amounts of heavy metal ion (3,21,35) and are not inhibited by reagents acting to chelate metals (3,11,10). This does not contradict the finding (35,47) that o-phenanthroline inhibits muscle aldolase, as Kobashi and Horecker have demonstrated (47) that the inhibition is caused by the oxidation of certain sulfhydryl groups.…”

Site-Specific Hydrogen Isotope Fractionation in the Biosynthesis of Glycerol

“…Another source of exchange with water, which has been shown to intervene in the absence of G3P (16,(33)(34)(35), involves the pro-S hydrogen of the CH 2 OH group of DHAP. Since this exchange enzymatically catalyzed by aldolase also affects DHAP molecules resulting from isomerization of the G3P moiety, it may be responsible for a loss of connectivity between H-4 of glucose and both the 1-pro-S site in signal A and the H 2 position of glycerol.…”

Aspects of Enzyme Mechanisms Studied by Nuclear Spin Relaxation Induced by Paramagnetic Probes

“…The value of +e may therefore be as great as 1.3 x 10-l 1 sec in the binary complex and as great as that of water (1.7 x sec) in the ternary enzymeMn-pyruvate complex, which enlarges the range of values of T to 3.5-6.68 (Table V). and the enzyme from yeast has been shown to be a zinc metalloenzyme (135,136). Recently (137) it has been found that the tightly bound zinc cpuld be replaced by manganese and cobalt to yield an active preparation.…”