It isn't a homework question. I'm just stuck with desulfhydrase reactions and am unable to find enough information in the usual places. Any external source on this topic would be helpful.
A desulfhydrase catalyzes the removal of hydrogen sulfide from a compound. So the answer is yes, but it's not the most-commonly annotated reaction for the enzyme cystathionine gamma-lyase.
I didn't know off-hand. Here's how I answered the question:
I searched Entrez Protein (or NCBI...whatever the thing's called) with the following terms:
And got three hits for isoforms of cystathionine gamma-lyase. I clicked on one of them and started reading. Key things I noted:
So it's a good question because, if people normally characterize this enzyme in terms of Met biosynthesis, then we don't have a desulfhydrase. But I trusted the thing was annotated properly and that the comment above was just too medicine-oriented (as much biochemical literature is).
So to really understand the enzyme itself I searched MetaCyc for the Enzyme Commission identifier 188.8.131.52.
This let's me easily visualize the catalyzed reaction. And the annotation spells it out clearly:
In addition to the reaction described in Ryan's answer, cystathionine beta-synthase (CBS) also catalyses a reaction that yields hydrogen sulfide. These two reactions are thought to be the major sources of hydrogen sulfide in mammals.