Glass capillary quantitative determination of N pi-methylhistidine in urine and muscles

Derivatization of posttranslationally modified amino acids

After a brief overview of posttranslational modifications of protein amino acids, the use of various derivatizing reagents for amino acid analysis is discussed. Derivatization and chromatographic separation of hydroxyproline, methylhistidine, and phosphorylated amino acids are discussed in detail to illustrate some of the strategies that can be applied to the analysis of posttranslationally modified amino acids.

Gas chromatographic determination of 1- and 3-methylhistidine in biological fluids

A gas chromatographic method for the determination of 1- and 3-methylhistidine in biological fluids was developed. The amino acid fraction containing 1- and 3-methylhistidine was isolated using ion-exchange chromatography. The amino acids were derivatized to N-trifluoroacetyl-O-isobutyl esters and analysed by gas chromatography with micropacked or capillary columns and an ionization-resonance detector. The conditions for the acylation of the histidines were studied and analyses of various derivatives such as N-trifluoroacetates, N-pentafluoropropionates and N-heptafluorobutyrates were tested. The detection limit of 1- and 3-methylhistidine was 50 ng per sample.

Increased myofibrillar protein catabolism in duchenne muscular dystrophy measured by 3-methylhistidine excretion in the urine

Myofibrillar protein catabolic rate was calculated in 50 young patients with Duchenne muscular dystrophy from the amount of 3-methylhistidine excreted in the urine, and was found to be about seven times that of a control series, expressed as the percentage of myofibrillar protein catabolized per day. This wastage of myofibrillar protein is a consequence of Duchenne muscular dystrophy and inhibition of protein degradation appears to be one possible approach in the treatment of this disease.

Derivatization reactions in the gas—liquid chromatographic analysis of drugs in biological fluids

Alkylation, acylation, silylation and other derivatization reactions applied to the gas chromatographic analysis of drugs in biological matrices are reviewed. Reaction conditions are discussed in relation to reaction mechanisms. Detector-oriented labelling of drugs, and derivatization with chiral reagents for the separation of enantiomers are surveyed. Data on the sample clean-up, derivatization and GLC analysis of more than 300 drugs and related compounds are listed.

Content of methylhistidines in normal and pathological human skeletal muscles

The content of 3-methylhistidine (3-MH) and 1-methylhistidine (1-MH) was measured in muscle biopsy specimens from 13 normal controls, 19 patients with Duchenne muscular dystrophy, 8 limb-girdle disease patients, and 23 disease controls with different forms of muscular pathology. 3-MH and 1-MH concentrations in normal human muscle did not appear to be influenced by sex, body weight, and age, at least for subjects in the 10--60 year age group examined. Skeletal muscle 1-MH levels did not significantly differ from mean control values in any of the pathologies investigated. In the patient population examined, the mean 3-MH level per unit of noncollagen protein (NCP) was significantly lower than normal in Duchenne dystrophy only, the reduction being related to disease severity. The significantly lower concentrations of 3-MH in muscle of Duchenne patients indicate the importance of measuring 3-MH in diseased muscle to obtain reliable estimates of the myofibrillar protein catabolic rate.