Plasma cyst(e)ine in homocyst(e)inemia.
Using a method developed to measure plasma protein-bound 1/2-cystine, we have observed that the metabolic state can affect the distribution of plasma cyst(e)ine between the bound and the free form. In five patients with homocyst(e)inemia, 1/2-homocystine was found to have replaced virtually all the cysteine normally present on sulfhydryl-binding sites of plasma proteins. The majority of the cyst(e)ine measured in the plasma of these patients (6.9 +/- 2.4 mumol/dl, mean +/- SD) was present in the form of a mixed disulfide with 1/2-homocystine (5.4 +/- 0.9 mumol/dl) rather than being free in the plasma or bound to plasma proteins.
D001798:Blood Proteins / Q000378:metabolism; D003545:Cysteine / Q000097:blood*; D003553:Cystine / Q000097:blood*; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006711:Homocystine / Q000097:blood*; D006712:Homocystinuria / Q000097:blood*; D006801:Humans; D008297:Male; D008715:Methionine / Q000097:blood; D011485:Protein Binding
D001798:Blood Proteins; D006710:Homocysteine; D006711:Homocystine; D003553:Cystine; D008715:Methionine; D003545:Cysteine