Neighboring Group Participation in the Transition State of Human Purine Nucleoside Phosphorylase
نویسندگان
چکیده
منابع مشابه
Ribocation transition state capture and rebound in human purine nucleoside phosphorylase.
Purine nucleoside phosphorylase (PNP) catalyzes the phosphorolysis of 6-oxy-purine nucleosides to the corresponding purine base and alpha-D-ribose 1-phosphate. Its genetic loss causes a lethal T cell deficiency. The highly reactive ribocation transition state of human PNP is protected from solvent by hydrophobic residues that sequester the catalytic site. The catalytic site was enlarged by repl...
متن کاملPurine Nucleoside Phosphorylase
Purine nucleoside phosphorylase (EC 2.4.2.1) from bovine spleen is a trimeric enzyme that readily dissociates to the monomer. Dilution of enzyme from 20 to 0.02 pg of protein/ml is accompanied by a greater than 50-fold increase in the specific activity (utrimer = 0.23 nmol/min/pg; umonomer = 12.5 nmol/min/pg). Gel permeation chromatography in the presence of the substrate phosphate shows the en...
متن کاملFour generations of transition-state analogues for human purine nucleoside phosphorylase.
Inhibition of human purine nucleoside phosphorylase (PNP) stops growth of activated T-cells and the formation of 6-oxypurine bases, making it a target for leukemia, autoimmune disorders, and gout. Four generations of ribocation transition-state mimics bound to PNP are structurally characterized. Immucillin-H (K*i(1/4) 58 pM, first generation)contains an iminoribitol cation with four asymmetric ...
متن کاملPurine nucleoside phosphorylase from human erythrocytes.
Purine nucleoside phosphorylase has been purified about 7,300-fold and crystallized from human erythrocytes (mol wt 81,000). The recrystallized enzyme exists in the form of needles and sometimes bundles of needles and has a specific activity of 96 pM units per mg of protein. A number of phenomena reported earlier for a less pure preparation of this enzyme are still seen with the crystalline enz...
متن کاملAchieving the ultimate physiological goal in transition state analogue inhibitors for purine nucleoside phosphorylase.
Genetic deficiency of human purine nucleoside phosphorylase (PNP) causes T-cell immunodeficiency. The enzyme is therefore a target for autoimmunity disorders, tissue transplant rejection and T-cell malignancies. Transition state analysis of bovine PNP led to the development of immucillin-H (ImmH), a powerful inhibitor of bovine PNP but less effective for human PNP. The transition state of human...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Biochemistry
سال: 2007
ISSN: 0006-2960,1520-4995
DOI: 10.1021/bi700147b