Trynda L, Pruchnik F
Institute of Chemistry, University of Wrocław, Poland.
J Inorg Biochem. 1995 Apr;58(1):69-77. doi: 10.1016/0162-0134(94)00040-h.
The interaction of Rh2(OAc)4 with human serum albumin (HSA) has been studied by absorption difference spectroscopy, CD spectroscopy, and quantitative precipitating HSA-antibody test. Our results demonstrate that this rhodium complex reacts easily with HSA at several ratios of reagents. The Rh atoms are coordinated to protein molecules via the imidazole rings of His residues. The structural studies have shown the conformational change of HSA modified by rhodium. Rhodium binding lowers the helicity of the native protein between 8 to 18% depending upon the molar ratios (from 1:1 to 10:1). Denaturation measurements of free HSA and HSA in the presence of dirhodium(II) acetate complex with 8-M urea followed by CD spectroscopy, suggest that rhodium affects the secondary protein structure and might stabilize HSA against denaturing agents. 8-M urea caused the unfolding of the native HSA secondary structure by about 40% and the structure of Rh(OAc)4-HSA by about 10%. The modification of native HSA by rhodium causes its decreased ability to precipitate with HSA antibodies. The decrease of antigenic properties can be connected with the unfolding of the antigen structure, which brings about perturbation of complementarity of the antigen-antibody reactive sites.
通过吸收差光谱法、圆二色光谱法和定量沉淀HSA抗体试验研究了Rh2(OAc)4与人血清白蛋白（HSA）的相互作用。我们的结果表明，这种铑配合物在几种试剂比例下很容易与HSA反应。铑原子通过组氨酸残基的咪唑环与蛋白质分子配位。结构研究表明了铑修饰的HSA的构象变化。根据摩尔比（从1:1到10:1），铑的结合使天然蛋白质的螺旋度降低8%至18%。在8-M尿素存在下，对游离HSA和铑（II）乙酸盐配合物存在下的HSA进行变性测量，随后进行圆二色光谱分析，结果表明铑会影响蛋白质的二级结构，并可能使HSA对变性剂具有稳定性。8-M尿素使天然HSA二级结构的展开约40%，使Rh(OAc)4-HSA的结构展开约10%。铑对天然HSA的修饰导致其与HSA抗体沉淀的能力下降。抗原特性的降低可能与抗原结构的展开有关，这会导致抗原-抗体反应位点互补性的扰动。
