RELATIONSHIP BETWEEN PALMITOYL-COENZYME-A SYNTHETASE-ACTIVITY AND ESTERIFICATION OF SN-GLYCEROL 3-PHOSPHATE IN RAT-LIVER MITOCHONDRIA
RELATIONSHIP BETWEEN PALMITOYL-COENZYME-A SYNTHETASE-ACTIVITY AND ESTERIFICATION OF SN-GLYCEROL 3-PHOSPHATE IN RAT-LIVER MITOCHONDRIA
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DOI：
10.1042/bj1320697
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发表时间：
1973-01-01
影响因子：
4.1
通讯作者：
BRINDLEY, DN
中科院分区：
文献类型：
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作者：
SANCHEZ, M;NICHOLLS, DG;BRINDLEY, DN
1.用大鼠肝线粒体测定了棕榈酰辅酶A合成酶和3-磷酸甘油酯与棕榈酰辅酶A内源合成酶和棕榈酰-(-)-肉碱辅酶A生成的棕榈酰辅酶A和过量的肉碱棕榈酰基转移酶的比活力。2.棕榈酰辅酶A合成酶的平均比活力约为棕榈酸甘油酯和棕榈酰-(-)-肉碱酯化反应速率的5倍和7倍。在不同的大鼠中，棕榈酰辅酶A合成酶的活性与3-磷酸甘油酯的酯化反应之间没有明显的相关性。然而，棕榈酸酯和棕榈酰肉碱合成甘油酯的速率之间存在显著的相关性(r=0.83P<；0.001)。3.棕榈酸酯合成的甘油酯的平均摩尔组成为：溶血磷脂酸盐58%，磷脂酸盐31%，中性脂11%。棕榈酰-(-)-肉碱的等效值分别为70%、23%和7%，差异显著。4.当线粒体在37℃预孵育后，棕榈酰辅酶A合成酶失活60-70%，对甘油脂的生物合成具有限速作用。加入1-5 mM-ATP可防止棕榈酰辅酶A合成酶失活。5.预培养对棕榈酸、棕榈酰辅酶A、棕榈酰肉碱和苹果酸+谷氨酸的氧化也有抑制作用。这些抑制作用不能通过添加三磷酸腺苷来阻止。6.棕榈酰辅酶A转化为棕榈酰基-(-)-肉碱不能抑制3-磷酸甘油的酯化反应。7.通过添加部分纯化的合成酶或肉碱棕榈酰转移酶和棕榈酰-(-)-肉碱，扩大了由棕榈酰辅酶A合成酶合成的棕榈酰辅酶A库。未见棕榈酸酯掺入甘油脂的刺激作用。8.在低浓度的镁离子、棕榈酸酯、三磷酸腺苷和辅酶A的作用下，棕榈酰辅酶A合成酶的反应速度比棕榈酸酯合成甘油脂的反应速度慢得多。9.在最适底物浓度下，大鼠肝线粒体中sn-甘油-3-磷酸酰基转移酶而不是棕榈酰辅酶A合成酶的活性对磷脂酸和溶血磷脂酸的合成具有限速作用。
1. The specific activities for palmitoyl-CoA synthetase and forsn-glycerol 3-phosphate esterification, with palmitoyl-CoA generated either by the endogenous synthetase or from palmitoyl-(-)-carnitine, CoA and excess of carnitine palmitoyltransferase, were measured with rat liver mitochondria. 2. The mean specific activity of palmitoyl-CoA synthetase was approximately five- and seven-fold the rates ofsn-glycerol 3-phosphate esterification from palmitate and palmitoyl-(-)-carnitine respectively. No significant correlation was found in different rats between the activities of palmitoyl-CoA synthetase andsn-glycerol 3-phosphate esterification from either acyl precursor. However, there was a significant correlation (r=0.83,P<0.001) between the rates of glycerolipid synthesis from palmitate and palmitoyl-(-)-carnitine. 3. The mean molar composition of the glycerolipid synthesized from palmitate was 58% lysophosphatidate, 31% phosphatidate and 11% neutral lipid. With palmitoyl-(-)-carnitine the equivalent values were 70, 23 and 7%, which were significantly different. 4. When palmitoyl-CoA synthetase had been inactivated by 60–70% after preincubation of mitochondria at 37°C, it became rate-limiting in glycerolipid biosynthesis. Additions of 1–5mm-ATP prevented inactivation of palmitoyl-CoA synthetase. 5. Preincubation also inhibited the oxidation of palmitate, palmitoyl-CoA, palmitoyl-(-)-carnitine and malate plus glutamate. These inhibitions could not be prevented by addition of ATP. 6. Diversion of palmitoyl-CoA to form palmitoyl-(-)-carnitine did not inhibitsn-glycerol 3-phosphate esterification. 7. The palmitoyl-CoA pool synthesized by the palmitoyl-CoA synthetase was augmented by adding partially purified synthetase or carnitine palmitoyltransferase and palmitoyl-(-)-carnitine. No stimulation of palmitate incorporation into glycerolipids occurred. 8. At low concentrations of Mg2+, palmitate, ATP and CoA the velocity with palmitoyl-CoA synthetase decreased more than that of glycerolipid synthesis from palmitate. 9. It is concluded that in the presence of optimum substrate concentrations the activity ofsn-glycerol 3-phosphate acyltransferase and not of palmitoyl-CoA synthetase is rate-limiting in the synthesis of phosphatidate and lysophosphatidate in isolated rat liver mitochondria.