9958, obtained for SAHH by plotting sample amounts in microliters of packed RBC vs total activity in pmol/s.
The ADA, PNP, and SAHH activities in RBCs from ADA/SCID patients and healthy individuals, expressed in terms of reaction product formation, are shown in Table 4.
SAHH activity was as low as 4% relative to that of healthy individuals (Table 4).
3] Nonstandard abbreviations: ADA, adenosine deaminase; Ado, adenosine; dAdo, 2'-deoxyadenosine; Ino, inosine; SCID, severe combined immunodeficiency disease; SAHH, S-adenosyl-L-homocysteine hydrolase; PNP, purine nucleoside phosphorylase; PEG, polyethylene glycol; CE, capillary electrophoresis; dAXP, deoxyadenosine nucleotide species; RBC, red blood cell; PCA, perchloric acid; Hyp, hypoxanthine; Xan, xanthine; and SAH, S-adenosylhomocysteine.
Chilling samples or storage at ambient temperature in the presence of a SAHH inhibitor (3DA) may both stabilize Hcy to some degree.
As the precursors to Hcy accumulate, SAHH inhibition by 3DA is finally overcome.
4] Nonstandard abbreviations: Hcy, homocysteine; 3DA, 3-deazaadenosine; and SAHH, S-adenosylhomocysteine hydrolase.