Alpha-keto acid is a bifunctional organic compound containing both carboxyl and ketone groups, and widely applied in the industries of food, pharmaceutical and cosmetics. Based on the demand of eco-friendly process, safety and sustainable development, production of α-keto acids by enzymatic conversion technology has been paid more and more attention. In this article, we review the status of α-keto acids biosynthesis from three aspects: enzymatic screening, enzymatic modification and optimization of enzymatic conversion conditions. Meanwhile, we also indicate future research directions for further improving α-keto acids production.
Keto Acids ; metabolism

Branched chain amino acids, as essential amino acids, can be used to synthesize nitrogen-containing compounds and also act as signal molecules to regulate substance metabolism. Studies have shown that the elevated level of branched chain amino acids is closely related to insulin resistance and type 2 diabetes. It can affect insulin signal transduction by activating mammalian target of rapamycin (mTOR) signal pathway, and regulate insulin resistance by damaging lipid metabolism and affecting mitochondrial function. In addition, abnormal catabolism of branched amino acids can lead to the accumulation of metabolic intermediates, such as branched chain α-keto acids, 3-hydroxyisobutyrate and β-aminoisobutyric acid. Branched chain α-keto acids and 3-hydroxyisobutyrate can induce insulin resistance by affecting insulin signaling pathway and damaging lipid metabolism. β-aminoisobutyric acid can improve insulin resistance by reducing lipid accumulation and inflammatory reaction and enhancing fatty acid oxidation. This paper systematically reviewed the regulatory effects and mechanisms of branched chain amino acids and their metabolic intermediates on insulin resistance, which will provide a new direction for the prevention and treatment of insulin resistance and type 2 diabetes.
Humans ; Amino Acids, Branched-Chain/metabolism* ; Insulin Resistance/physiology* ; Diabetes Mellitus, Type 2 ; Insulin/pharmacology* ; Keto Acids/metabolism*

OBJECTIVETo investigate the effects of alpha-keto acid on the expression of neuropeptide Y in malnutrition rats with chronic renal failure.

METHODSSD rats received 5/6 nephrectomy and were fed with 4% casein to establish models of malnutrition with chronic renal failure. Serum albumin, urea nitrogen, serum creatinine, type-1 insulin like growth factor and body weight of the rats were measured. The rat models were randomized into chronic renal failure group, alpha-keto acid group and normal control group, and after a 4-week treatment as indicated, neuropeptide Y mRNA levels in the hypothalamus were measured by RT-PCR in rats with surgically induced renal failure (two-stage subtotal nephrectomy). The blood neuropeptide Y of the rats were analyzed by radioimmunoassay.

RESULTSMalnutrition occurred in chronic renal failure rats at the end of 10 weeks. Compared with those in the chronic renal failure group, the plasma neuropeptide Y concentrations in alpha-keto acid group were significantly lowered with substantially elevated neuropeptide Y mRNA expression in the hypothalamus.

CONCLUSIONalpha-keto acid capsule can improve malnutrition in rats with renal insufficiency possibly by up-regulating neuropeptide Y mRNA expression in the hypothalamus and reducing the level of blood neuropeptide Y.

Animals ; Hypothalamus ; metabolism ; Keto Acids ; pharmacology ; therapeutic use ; Kidney Failure, Chronic ; blood ; Male ; Malnutrition ; blood ; drug therapy ; Neuropeptide Y ; blood ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley