황소개구리(Rana catesbeiana) I (2월)과 II (8월) 조직의 젖산탈수소효소(EC. 1.1.1.27, lactate dehydrogenase, LDH) 동위효소의 발현 및 역학적 특성을 확인하였다. I의 골격근에서 LDH 활성, A4 동위효소 및 LDH/CS (EC 4.1.3.7, citrate synthase)가 높게 측정되었고, II의 여러 조직에서 LDH B4 동위효소의 활성이 증가되었으며, 특히 심장과 뇌조직에서 LDH 활성이 크게 확인되었다. 면역침강반응 후 native-PAGE에 의해 눈조직에서 LDH eye-specific C 동위효소가 확인되었고, LDH C가 LDH B에 유사한 것으로 확인되었다. LDH A4 동위효소를 oxamate-linked affinity chromatography로 정제하였고, 하부단위체 A의 분자량은 32.0 kDa이었다. II의 LDH는 KmPYU이 높았고, 심장과 뇌조직의 VmaxPYU이 높았으며, 조직들의 VmaxLAC도 높고, 젖산에 대한 내성이 큰 것으로 확인되었다. 그리고 정제한 A4 동위효소와 눈조직 LDH가 젖산에 대한 내성이 가장 크게 확인되었다. KmLAC가 KmPYU보다 컸다. 피루브산 10 mM에 의해 I, II 조직 LDH의 하부단위체 B의 비가 증가함에 따라 LDH 활성의 억제정도가 높았다. 실험 결과, 황소개구리에서 LDH eye-specific C가 확인된 것이 특징적이었고, 황소개구리 I의 골격근 LDH의 활성이 높아 혐기적 대사가 우세하였으며, 황소개구리 II의 경우 LDH B가 증가되고 젖산에 대한 내성이 커져 잘 적응되어진 것으로 사료된다.
The kinetic properties and isozyme expression of lactate dehydrogenase (EC 1.1.1.27; LDH) in tissues from Rana catesbeiana I and II collected from February (I) and August (II) were studied. LDH activities, A4 isozyme, and LDH/citrate synthase (EC 4.1.3.7; CS) were high in skeletal muscle from R. catesbeiana I, and LDH B4 isozyme increased in several tissues of R. catesbeiana II. In particular, LDH activities were high in heart and brain tissues from R. catesbeiana II. LDH eye-specific C isozyme, detected by native polyacrylamide gel electrophoresis after immunoprecipitation, was expressed in eye tissue and was more similar to the B4 than A4 isozyme. LDH A4 isozyme was purified by oxamate-linked affinity chromatography, and the molecular weight of subunit A was 32.0 kDa. In R. catesbeiana II, levels of KmPYU, VmaxLAC, and tolerance to lactate of LDH were high in all tissues, and VmaxPYU of LDH in heart and brain tissue was highly detected. Purified A4 isozyme and LDH in eye tissue were highly tolerate compared to others. The KmLAC value was highly measured compared to KmPYU. The degree of inhibition by 10 mM of pyruvate on LDH activities in tissues from R. catesbeiana I and II was more pronounced as the ratio of subunit B increased. As a result, characteristic expression of LDH eye-specific C was found in R. catesbeiana. Anaerobic metabolism seemed to predominate as the LDH of skeletal muscle from I showed higher activity. It also appeared that R. catesbeiana II adapted well to incremental increases in LDH B, becoming tolerant to the lactate of LDH in tissues.