ABSTRACT
Chiral amino acid analysis is a sensitive, efficient and economical method for controlling racemic peptide impurities, especially for synthetic polypeptide drugs with complex composition of amino acids. Unexpected amino acid enantiomers in racemic peptides can be measured by chiral amino acid analysis coupled with mass spectrometry. The position of amino acid isomerization in the peptide segment can be accurately mapped by mass spectrometry, which lays a solid foundation for screening of racemic peptide impurities and rapid identification or quantification of trace racemic peptide impurities. Combination of the two techniques is vital for quality control of the synthetic polypeptide drugs and for research of polypeptide drugs based on chemical synthesis. The strategies of peptide hydrolysis have been summarized in this review. The latest chiral amino acid analysis based on mass spectrometry is briefly reviewed. Based on our knowledge, we have pointed to the direction of research and control of racemic peptide impurities in synthetic polypeptide drugs.
ABSTRACT
Objective To establish a method for fingerprint analysis of amino acids from honey by high performance liquid chromatography ( HPLC). Methods Amino acids of honey were concentrated by 732 cation exchange resin, and then were treated by pre-column derivatization with phenyl isothiocyanate, with praline as control peak. The chromatography was performed on a Waters Symmetry C18 ( 250 mm × 4.6 mm × 5 μm) column, with acetonitrile ∶ water (4∶1) as mobile phase A and 30 mmol/L sodium acetate ∶ acetonitrile (355∶15, acetic acid adjusting pH value to be 6.5) as mobile phase B by gradient elution. The detection wave length was set at 254 nm. The flow rate was 1.0 mL/min. The column temperature was 40℃, and the injection volume was 5μL. Results Sixteen common peaks were shown in the fingerprint of 15 batches of honey samples. The similarity for 15 batches of honey samples was in the range of 0.910 ~ 0.996 . Conclusion The fingerprint detection method is simple, practical, reproducible and specific, and can provide certain reference for quality control of honey.
ABSTRACT
【Objective】To compare the fingerprint spectrum of amino acids(AA)of Lignum Santali Albi(LSA)from Indonesia,India and Australia.【Methods】Free AA and hydrolytic AA of LSA from Indonesia,India and Australia were analyzed by amino acid automatic analyzer.The detection wavelength was 570nm and 440nm.【Results】There were obvious differences among the free AA from three kinds of LSA.2S,4S-4-hydroxyproline(Hyp)was detected in Indonesian LSA in 11.77min(?=440nm)with the content of 1.431?7%,and became proline after hydrolysis.The peak of Hyp was not obvious or even undetectable in Indian LAS and Australian LSA.【Conclusion】There exist obvious differences among free AA from three kinds of LSA and 2S,4S-4-Hyp can be used as the specific compounds for the identification of LSA from Indonesia,India and Australia.
ABSTRACT
Objective To monitor the release of amino acids of the whole retina during and after experimental glaucoma by increasing the intraocular pressure (IOP). Methods Experimental glaucoma was induced in one of the two eyes of rabbits by increasing IOP at 120 mm Hg for 45 min under infusion of saline in anterior chamber;then the pressure was released and the needle inserted into the anterior chamber was removed,this state was maintained for another 45 min.Every 15 min during the experiment 5 rabbits were killed and experimental eyes were enucleated.Aliquots (20 ?l) of the retinal extracts (see below) were mixed with ophthaldialdehyde reagent and analysed for amino acid content by the HPLC method of Wangwei, using a 150 mm?4.6 mm,5 ?m C18 column. Results A large increase in the release of glutamate,but not of the other three amino acids monitored,occurred during initial experimental ocular hypertension.It reached peak value of (111.73?17.46) 10 -5 mmol/g at 15 min of hypertension.15 min after release of intraocular pressure,again,immediately large and specific increase in the concentration of glutamate was reached to (102.96?51.91) 10 -5 mmol/g.In eyes subjected to paracentesis of anterior chamber,no difference was found between experimental eyes and controls. Conclusion These results suggest that glutamate is triggered by increasing the IOP,and it releases not only during the period of experimental ocular hypertension,but also afterwards.