포유류 혈장알부민의 이질성

Heterogeneity of Mammalian Plasma Albumin

소의 혈장으로부터 알부민을 순수 정제하였으며 순도는 면역 화학적 방법을 사용하여 확인하였다. 정제된 알부민에 maleate, iodoacetate, iodoacetamide 및 glutathione의 4가지 thiol 화합물을 각각 반응시켜 그 복합체를 9가지의 상이한 완충용액내에서 초산셀룰로우즈 전기영동한 결과 barbital buffer와 Na-acetate buffer를 제외한 다른 완충용액내에서 albumin-glutathione 복합체는 두 가지의 단백질로 분리되었으며 pH 4.8 citrate buffer 및 pH 4.8 succinate buffer내에서 albumin-iodoacetate 및 albumin-iodoacetamide 복합체는 두 가지의 단백질로 분리되었다. 전기영동상에 나타나는 알부민 분획에는 conformation이 서로 다른 두 가지 이상의 알부민 분자가 존재한다고 사료된다.

Plasma albumin was purified from the fresh bovine blood using a minor modification of the polyethyleneglycol and ethanol procedure. The resulting protein solution was tested for its purity by both electrophoretic and immunochemical methods and found to contain only the albumin molecules. Each of the four thiol reagents, maleate, iodoacetate, iodoacetamide and glutathione, was incubated with the purified plasma albumin. The electrophoresis on cellulose acetate of those complexes in various buffers with different component and pH demonstrated that the albumin-glutathione complex was separated into two zones in all buffers used except the barbital and sodium acetate buffers, that the complexes of albumin-iodoacetate and albumin-iosoacetamide also into two zones only in pH 4.8 citrate buffer and in pH 4.8 succinate buffer and that the new zone had more positive net charge compared to the native protein in any case. These results might suggest a possibility that the electrophoretic albumin fraction is composed of at least two molecular species with different conformation.