The Fate of Proteins
Almost immediately after digestion, amino acids are reassembled into proteins to serve as enzymes, transporting proteins (hemoglobin), antibodies, clotting chemicals (fibrinogen), hormones (insulin), actin and myosin; and structural components such as collagen, elastin, keratin.
Protein Catabolism
Some protein catabolism occurs in our bodies’ every day. Proteins from worn-out RBCs are broken down into AAs. Hepatocytes convert some amino acids to fatty acids or glucose. Cells throughout the body oxidize a small amount of amino acids to produce ATP via the Krebs cycle and ETC. Before amino acids can be oxidized, they must first be converted to molecules that are part of the Krebs cycle or can enter the Krebs cycle such as Acetyl CoA. Before they can enter, their amino group must first be removed, a process called Deamination which occurs in hepatocytes and produces ammonia (NH3). The liver cells then convert the highly toxic ammonia to urea, a harmless substance excreted in our urine. The conversion of amino acids into glucose (gluconeogenesis) can occur.
Protein Anabolism
This is the formation of peptide bonds b/t amino acids to produce new proteins and is carried out on the ribosomes of almost every cell in the body directed by the cells DNA and RNA (as you know ). Various hormones stimulate protein synthesis. Because proteins are a main component of most cell structures, adequate dietary intake is essential during growth years, during pregnancy and when tissue has been damaged by disease or injury.
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