큰입우럭(Micropterus salmoides) 조직의 젖산탈수소효소 및 Monocarboxylate 수송체(MCT) 1, 2, 4 (Lactate Dehydrogenase and Monocarboxylate Transporters 1, 2, and 4 in Tissues of Micropterus salmoides)

서지정보

· 발행기관 : 한국생명과학회
· 수록지 정보 : 생명과학회지 / 22권 / 1호 / 98 ~ 109페이지
· 저자명 : 염정주, 연준희

초록

큰입우럭(Micropterus salmoides) 조직의 젖산탈수소효소(EC 1.1.1.27, LDH)의 특성 및 골격근과 심장조직의 monocarboxylate 수송체 1, 2, 4의 발현을 연구하였다. Native-PAGE 결과골격근에서 LDH A4, 심장, 간, 눈 및 뇌조직에서 A4, A2B2, B4, 눈조직에서 eye-specific C4 동위효소가 발현되었다. 9월에 심장조직에서 LDH B4 동위효소의 활성이 강하고 다른 조직에서는 A4의 활성이 강했으나, 11월에 심장조직에서 A4 동위효소의 활성이 강하게 확인되었다. 골격근과 심장조직에서 LDH/CS로 조직의 혐기적 대사 비율이 높게 확인되었으며, 면역 침강 후 native-PAGE에 의해 LDH eye-specific C4 동위효소가 B4보다 A4 동위효소에 더 유사한 것으로 확인되었다. LDH A4 동위효소가 affinity chromatography에 의해 정제되었고, 하부단위체 A의 분자량은 37.200이었다. 피루브산 10 mM에서 조직 LDH의 활성이 11.05-28.32% 남아 저해 정도가 컸고, 눈조직 LDH의 KmPYR이 낮았으며, 조직의 최적 pH는 7.5~8.0이였다. 골격근 미토콘드리아에서 LDH A4 동위효소, 심장조직의 미토콘드리아에서 B4와 A2B2동위효소가 확인되었고, 골격근과 심장조직의 원형질막과 미토콘드리아에서 MCT 1, 2, 4가 확인되었다. 골격근 MCT 1, 2, 4 골격근 MCT 1 60 kDa, MCT 2 54~38 kDa, MCT 4 63 kDa, 심장조직 MCT 1 57 kDa, MCT 2 54~38 kDa 및 MCT 4 55.5 kDa이었다. 실험 결과, 큰입우럭이 저산소 조건에 적응되어져 혐기적 대사가 우세하고, 활성이 큰 골격근과 심장조직에서 원형질막과 미토콘드리아 MCT 1, 2, 4를 통해 젖산과 피루브산이 유입되고 유출되며 LDH에 의해 에너지 생성을 효율적으로 조정하는 것으로 사료된다.

영어초록

The properties of lactate dehydrogenase (EC 1.1.1.27, LDH) and expression of monocarboxylate transporters (MCTs) 1, 2, and 4 were studied in tissues from Micropterus salmoides. Native-PAGE revealed that the LDH A4 isozyme was predominantly located in skeletal muscle. The LDH A4, A2B2, and B4 isozymes were detected in heart, liver, eye, and brain tissues, while eye-specific C4 isozyme was detected in eye tissue. In September, strong LDH B4 isozyme activity was detected in heart tissue. High A4 isozyme activity was noted in all other tissues except heart tissue. However, in November, strong A4 isozyme activity was detected in heart tissue. The LDH/CS (Citrate synthase, EC 4.1.3.7) ratio in skeletal muscle and heart tissues indicated that anaerobic metabolism was high in those tissues. Native-PAGE after immunoprecipitation showed that eye-specific C4 isozyme was more similar to the A4 than the B4 isozyme. The LDH A4 isozyme was purified by affinity chromatography. The molecular weight of subunit A was 37,200. The LDH activity in tissues was consistently 11.05~28.32% due to inhibition by 10 mM pyruvate. The KmPYR of LDH in eye tissue was very low. The optimum pH for LDH in tissues was pH 7.5~8.0. The LDH A4 isozyme was detected in mitochondria of skeletal muscle, whereas the B4 and A2B2 isozymes were detected in heart tissue mitochondria. Western blot analysis indicated that MCTs 1, 2, and 4 were located in the plasma membrane and mitochondria of skeletal muscle and heart tissues. The sizes of MCTs 1, 2, and 4 in skeletal muscle were 60, 54~38, and 63 kDa, while those in heart tissue were 57, 54~38, and 55.5 kDa, respectively. In conclusion, M. salmoides appears to use anaerobic metabolism predominantly when adapted to a hypoxic environment. In highly activated skeletal muscle and heart tissue, energy production is controlled by inward and outward flows of pyruvate and lactate through MCTs 1, 2, and 4 in the plasma membrane and mitochondria, with effective adjustment by LDH isozymes.

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