Human Cysteine Metabolism
In human cysteine metabolism, L-cysteine is consumed in several ways as shown below. L-cysteine is also consumed in methionine and glutathione metabolism as well as pantothenate/CoA biosynthesis.
| Enzyme | → | Product |
|---|---|---|
| cysteine dioxygenase | → | 3-sulfino-L-alanine (or cysteine sulfinic acid) |
| amino-acid racemase | → | D-cysteine |
| cysteine lyase | → | L-cysteate |
| cysteine—tRNA ligase | → | L-cysteinyl-tRNACys |
| cystine reductase | → | L-cystine |
| cysteine transaminase | → | 3-mercapto-pyruvate |
L-cysteine is the product of several processes as well. In addition to the reactions below, L-cysteine is also a product of glycine, serine, and threonine metabolism.
| Starting chemical | → | Enzyme |
|---|---|---|
| O-acetyl-L-serine | → | cysteine synthase |
| L-cystine | → | glutathione-cystine transhydrogenase |
| pyruvate | → | cystathionine γ-lyase |
| 3-mercapto-pyruvate | → | cysteine transaminase |
Read more about this topic: Cysteine Metabolism
Famous quotes containing the words human and/or metabolism:
“The real essence, the internal qualities, and constitution of even the meanest object, is hid from our view; something there is in every drop of water, every grain of sand, which it is beyond the power of human understanding to fathom or comprehend. But it is evident ... that we are influenced by false principles to that degree as to mistrust our senses, and think we know nothing of those things which we perfectly comprehend.”
—George Berkeley (1685–1753)
“He’s got a fifteen percent metabolism with an overactive thyroid and a glandular affectation of about three percent. With a one percent mentality. He’s what we designate as the Crummy Moronic type.”
—Robert Pirosh, U.S. screenwriter, George Seaton, George Oppenheimer, and Sam Wood. Dr. Hugo Z. Hackenbush (Groucho Marx)