Lanthionine, decarboxylating

The supernatant was additioned with ammonium sulfate till a S5% saturation,the precipitate,collected by centrifugation,was dissolved in 10 mM Tris-Cl buffer pH 8 made 0.1 niM in pyridoxal-5 -phosphate and dialyzed overnight against the same buffer.Clarified by centrifugation,the solution was applied to a DEAE(DE-23)cellulose column equilibrated and eluted with 10 mM Tris-Cl buffer pK 8.The lanthionine decarboxylating activity was found in the tail of the second eluted peak,as reported in Fig.2.Concentrating by pressure dialysis the protein solution containing the activity,this was not retained... 

Many additional examples of the elucidation of prostereoisomerism in biochemical reactions could be given, for example the elegant elucidation by Comforth and coworkers 111, n8,137) of the biosynthesis of squalene, which was recognized by the Nobel prize in chemistry in 1975, or the recent studies of the enzymatic decarboxylation of tyrosine 138) and histidine 139) and of the condensation of homoserine with cysteine to give lanthionine 140), but the examples already provided should illustrate the principles and techniques involved in such studies. 

The one side decarboxylation of lanthionine could yield aminoethylcysteine(AEC)which is known as a precursor of taurine when injected into rats(20). 

C-lanthionine,obtained by reaction of C-cysteitie with j3-chloroalanine as reported previously(21),when incubated with animal tissues produces C02,demonstrating the presence of a decarboxylating activity in all animal tissues the most efficient being rat and beef kidney(21). 

The experimental results reported demonstrate that in beef kidney cortices is present a small protein operating a one-side decarboxylation of lanthionine with the production of aminoethylcysteine which is furtherly degraded into cysteamine,hypotaurine and taurine as previously reported(21).At the present time cannot be claimed that this decarboxylase is specific toward lanthionine its activity on lanthionine could be an ancillary activity of another decarboxylase.However this activity on lanthionine demonstrate the presence in animal tissues of a new route which,via cysteamine,contributes to taurine pool.These results further confirm that cysteamine pathway appears to be the most important route... 

Sulfur-containing amino acids related to cysteine and methionine are cysteic add and its decarboxylation product taurine. Lanthionine, with one sulfur atom less than cystine, has been isolated from wool hydrolyzates. Homocystdne is the de-methylation product of methionine. 

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