【摘要】 目的研究肝素酶I的理化性质。方法测定肝素酶I的相对分子质量、等电点、紫外吸收光谱、N端序列,以及各种环境因素对酶活性和酶稳定性的影响。结果相对分子质量约为43×103,等电点为8.5。N端序列不能测到。酶的最适催化条件为:温度45℃,pH6.4～7.0,离子强度150mmol/L。酶在35℃以上极易失活,在pH7～11之间基本稳定。该酶的最大紫外吸收位于280nm。H2O2(1mmol/L,10mmol/L),NaN3(10mmol/L,100mmol/L),乙腈(1%,10%),1mol/L盐酸胍和1mol/L尿素对酶的活性无影响;1%SDS,4mol/L盐酸胍和4mol/L尿素则使酶完全失活;CaCl2和MgCl2是该酶的激活剂,FeCl2则对该酶的活性具有抑制作用。结论通过实验,测定了肝素酶I的主要理化性质。更多还原

【Abstract】 Objective To study physico-chemical properties of heparinase I.Methods Properties of the enzyme including relative molecular mass,isoelectric point,N-terminal amino acid sequence,optimal temperature and pH,UV absorbance,and the influence of the environment factors on activity and stability of the enzyme were determined.Results The enzyme had a relative molecular mas of 43×103 and the pI was about 8.5.The N-terminal amino acid sequence could not be determined.It had an activity maximum at pH6.4～7.0 and 41℃.The enzyme with a maximum UV absorbance at 280 nm was very sensitive to thermal denaturation at temperature up to 35 ℃.H2O2(1 mmol/L,10 mmol/L),NaN3(10 mmol/L,100 mmol/L),acetonitril(e1%,10%),1mol/L carbamidine hydrochlo-ride and 1mol/L urea had no influence on the activity of the enzyme.The enzyme was sensitive to 1% SDS,4mol/L carbamidine hydrocloride and 4mol/L urea.CaCl2 and MgCl2 were two activators of the enzyme,while FeCl2 was an inhibitor.Conclusion The main physico-chemical properties of heparinase I are clear by experiments.更多还原