Dipeptide amino acids
A dipeptide is a peptide that is composed of two amino acid molecules linked by a peptide bond.
Anserine (beta-alanyl-N-methyl histidine) is found in the
skeletal muscle and brain of birds.
Aspartame (N-L-a-aspartyl-L-phenylalanine 1-methyl ester) is an artificial sweetener.
Balenine (or ophidine) (beta-alanyl-N tau-methyl histidine) has been identified in the muscles of several species of mammal (including man), and the chicken.
Carnosine (beta-alanyl-L-histidine) is highly concentrated in muscle and brain tissues.
Homoanserine (N-(4-Aminobutyryl)-L-histidine) is another dipeptide identified in the brain and muscles of mammals.
Kyotorphin (L-tyrosyl-L-arginine) is a neuroactive dipeptide which plays a role in pain regulation in the brain.
Profiling histidine dipeptides in plasma and urine after
ingesting beef, chicken or chicken broth in humans.
Amino Acids. 2009. Yeum KJ, Orioli M, Regazzoni L, Carini M, Rasmussen H, Russell RM, Aldini G. Jean Mayer USDA, Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA.
The in vitro metabolic stability of histidine-dipeptides, carnosine and anserine, in human serum, and their absorption kinetics after ingesting pure carnosine or histidine dipeptide rich foods in humans have been investigated. Healthy women went through four phases of taking one dose of either 450 mg of pure carnosine, 150 g beef (B), 150 g chicken (C), or chicken broth (CB) from 150 g chicken with a >2-week washout period between each phase. Blood samples were collected at 0, 30, 60, 100, 180, 240, and 300 min, and urine samples before and after ingesting pure carnosine or food. Both plasma and urine samples were analyzed for histidine dipeptides concentrations. Carnosine was undetectable in plasma after ingesting pure carnosine, B, C or CB. By contrast, plasma anserine concentration was significantly increased after ingesting C or CB, respectively. Urinary concentrations of both carnosine and anserine were 13- to 14-fold increased after ingesting B, and 14.8- and 243-fold after CB ingestion, respectively. Thus, dietary histidine dipetides, which are rapidly hydrolyzed by carnosinase in plasma, and excreted in urine, may act as reactive carbonyl species sequestering agents.
Structures of dipeptides: the head-to-tail story.
Acta Crystallogr B. 2010; Görbitz CH. Department of Chemistry, University of Oslo, Norway.
The hydrogen-bonding patterns in crystal structures of unprotected, zwitterionic dipeptides are dominated by head-to-tail chains involving the N-terminal amino groups and the C-terminal carboxylate groups. Patterns that include two concomitant chains, thus generating a hydrogen-bonded layer, are of special interest. A comprehensive survey shows that dipeptide structures can conveniently be divided into only four distinct patterns, differing by definition in the symmetry of the head-to-tail chains and amide hydrogen-bonding type, but also in other properties such as peptide conformation and the propensity to include solvent water or various organic guest molecules. Upon crystallization, the choice of pattern for a specific dipeptide is not random, but follows from the amino acid sequence.