Jawaid Safdar, Gertz Monica, Corsino Carlin, Cheung Jamie, Seidle Heather, Couch Robin D
Chemistry and Biochemistry Department, George Mason University, Manassas, VA 20110, USA.
Indian J Biochem Biophys. 2010 Dec;47(6):331-9.
While statins, hydroxymethylglutaryl-coenzyme A reductase (HMGCR) inhibitors, are clinically proven to reduce plasma cholesterol levels, a wide variation in inter-individual response to statin therapy has been observed. Pharmacogenetic studies have identified multiple loci that potentially contribute towards the statin response, including the HMGCR gene. To examine, if a statin-resistant, catalytically-active isoform of the human HMGCR could be generated, we have rationally altered the protein to include additional residues in the flap domain, which has a role in statin binding. Comparative enzyme assays with purified wild-type and mutant isoforms reveal the alteration imposes a slight (38%) decrease in the K(app)(M) for the substrate, a near 2-fold increase in turnover number, and a 480% increase in the Ki for lovastatin. Thus, alterations in HMGCR could contribute towards the synergistic effects of multiple loci in the statin response.
虽然他汀类药物（羟甲基戊二酰辅酶A还原酶（HMGCR）抑制剂）在临床上已被证明可降低血浆胆固醇水平，但已观察到个体对他汀类药物治疗的反应存在很大差异。药物遗传学研究已确定多个可能影响他汀类药物反应的基因座，包括HMGCR基因。为了研究是否可以产生一种对他汀类药物耐药的、具有催化活性的人类HMGCR异构体，我们合理地改变了该蛋白，使其在瓣片结构域中包含额外的残基，该结构域在他汀类药物结合中起作用。对纯化的野生型和突变型异构体进行的比较酶分析表明，这种改变使底物的表观米氏常数（K(app)(M)）略有降低（38%），周转数增加近2倍，洛伐他汀的抑制常数（Ki）增加480%。因此，HMGCR的改变可能有助于多个基因座在他汀类药物反应中的协同作用。
