Lipidszintézis

Lipidszintézis, also known as lipid synthesis or lipogenesis, is the metabolic process by which organisms create lipids. This complex pathway involves the formation of fatty acids and their subsequent esterification to form more complex lipids such as triglycerides and phospholipids. The primary site for de novo fatty acid synthesis in mammals is the liver, adipose tissue, and lactating mammary glands. In plants, this process occurs mainly in the chloroplasts.

The synthesis of fatty acids begins with acetyl-CoA, a two-carbon molecule derived from carbohydrate metabolism, particularly from pyruvate. Acetyl-CoA is transported from the mitochondria to the cytoplasm, where it is carboxylated to malonyl-CoA by the enzyme acetyl-CoA carboxylase. This is the rate-limiting step of fatty acid synthesis. Subsequently, a multi-enzyme complex called fatty acid synthase catalyzes the sequential addition of two-carbon units from malonyl-CoA to a growing fatty acid chain, using reducing power from NADPH. The most common saturated fatty acid synthesized is palmitate, a 16-carbon fatty acid.

Triglycerides, the main form of stored fat, are synthesized in the liver and adipose tissue from glycerol-3-phosphate and fatty acyl-CoA molecules. Phospholipids, essential components of cell membranes, are synthesized through similar pathways, incorporating a phosphate group and a head group. Lipidszintézis is a crucial process for energy storage, membrane structure, and signaling pathways. It is tightly regulated by hormones such as insulin, which promotes lipid synthesis, and glucagon and epinephrine, which inhibit it.