AI Summary & Key Takeaways
AI InsightIt was found that the pyruvate kinase activity in tumor tissue was 5.2 times higher than that in normal tissue.
📌 3 Key Takeaways
Abstract
The molecular weight and kinetic properties of pyruvate kinase purified from human normal and tumor breast tissues were studied and the activity levels of pyruvate kinase from normal and tumor breast tissues were compared. The presence of 2 forms of pyruvate kinase in human breast tissue was demonstrated by DEAE Sephadex A-50 chromatography. The molecular weight of subunits estimated by SDS-PAGE in forms I. and II. in normal breast tissue and in forms I. and II. in tumor breast tissue were 30,000 and 63,000 Da and 16,500 and 60,000 Da, respectively. It was found that the pyruvate kinase activity in tumor tissue was 5.2 times higher than that in normal tissue. Peaks I and II of pyruvate kinase were able to be purified about 1591-fold and 636.4-fold in normal breast tissue, and 219-fold and 318-fold in tumor breast tissue, respectively. The reaction rate curve was hyperbolic in the first peaks of both normal and tumor breast tissue pyruvate kinase and was not activated by fructose-1, 6-diphosphate (FDP). Reaction rate curves in the second peaks of tumor breast tissue and normal breast tissue pyruvate kinase were hyperbolic and sigmoidal, respectively, and were activated by FDP. The Hill coefficient showed that there were at least 2 binding regions in the enzyme for PEP. When compared with other tissue pyruvate kinase isozymes, it seems likely that the isoenzymes of pyruvate kinase isolated from human breast tissue were M, and M2 isozymes and that the M2 isozyme of pyruvate kinase from normal breast tissue changed into K isoenzyme in tumor breast tissue.
Özet
İnsan normal ve tümör meme doku pirüvat kinazı saflaştırılarak moleküler ağırlığı ve kinetik özellikleri araştırılmış, normal meme dokusu ile tümör meme dokusu pirüvat kinaz aktivite düzeyleri karşılaştırılmıştır. DEAE Sefadeks A-SO kromatografi ile meme dokusunda pirüvat kinazın iki farklı formunun varlığı gösterilmiştir. SDS-PAGE ile alt birimlerinin moleküler ağırlığı normal dokuda 1. pikte 30.000 Da, II. pikte 63.000 Da, tümör dokusunda ise 1. pikte 16.500 Da, II. pikte 60.000 Da olarak saptanmıştır. Pirüvat kinaz aktivitesi tümör meme dokusunda normal meme dokusuna göre 5,2 kat fazla bulunmuştur. Pirüvat kinaz enzimi normal meme dokusunda 1. pik 1591 kat, II. pik 636,4 kat, tümör dokusunda I. pik 219 kat, II. pik ise 318 kat saflaştırılabilmiştir. Reaksiyon hız eğrisi normal ve tümör meme dokusu pirüvat kinazının 1. pikinde hiperbolikti ve FDP tarafından aktive edilmemiştir. II. pikte reaksiyon hız eğrisi tümör meme dokusunda hiperbolik, normal meme dokusunda ise sigmoidaldır ve FDP tarafından aktive edilmiştir. Hill katsayısı PEP için enzimde en az iki bağlanma bölgesinin varlığını göstermiştir. İnsan meme dokusundan izole edilen pirüvat kinaz izoenzimleri diğer doku pirüvat kinaz izoenzimleri ile karşılaştırıldığında bunların M, ve M2 izoenzim olduğu ve normal meme dokusundaki M2 izoenzimin tümör meme dokusunda K izoenzime dönüşebileceği düşünülebilir.