Biomaterial Database

Evaluation of a simple colorimetric assay for serum angiotensin-converting enzyme: comparison with a new ion-pair liquid chromatography-assisted assay. 1982

E Kwarts, and G Beukenveld, and J Gazendam

The development and validation of two different assays for serum angiotensin-converting enzyme are reported. The first step in both analytical systems is based on enzymatic cleavage of the synthetic substrate, hippuryl-histidyl-leucine, under conditions advocated by Cushman and Cheung. The hippuric acid released is then assayed either by colorimetry following an azlactone condensation reaction with an aromatic aldehyde, or by reversed-phase ion-pair high-performance liquid chromatography (HPLC). Both procedures reveal good linearity in the range 0-80 nmol/ml per min, with an inter-assay coefficient of variation of 6.2% for the colorimetric assay and 4.5% for the HPLC-assisted assay. Recovery values measured for the colorimetric method ranged from 97% to 102% and for the HPLC-assisted method from 98% to 101%. The colorimetric method is suitable for performance in small hospital laboratories since it can be carried out with simple analytical instrumentation. It is obvious nevertheless, that the HPLC-assisted assay reveals better validation criteria. The method is also simple and rapid and it has successfully been used in our laboratory for the last two years.

UI	MeSH Term	Description	Entries
D007703	Peptidyl-Dipeptidase A	A peptidyl-dipeptidase that catalyzes the release of a C-terminal dipeptide, oligopeptide-\|-Xaa-Yaa, when Xaa is not Pro, and Yaa is neither Asp nor Glu. Thus, conversion of ANGIOTENSIN I to ANGIOTENSIN II, with increase in vasoconstrictor activity, but no action on angiotensin II. It is also able to inactivate BRADYKININ, a potent vasodilator; and has a glycosidase activity which releases GPI-anchored proteins from the membrane by cleaving the mannose linkage in the GPI moiety. (From https://www.uniprot.org April 15, 2020).	ACE1 Angiotensin-Converting Enzyme 1,ACE1 Protein,Angiotensin Converting Enzyme,Angiotensin Converting Enzyme 1,Antigens, CD143,CD143 Antigens,Dipeptidyl Carboxypeptidase I,Kininase II,Peptidase P,Angiotensin I-Converting Enzyme,Carboxycathepsin,Dipeptidyl Peptidase A,Kininase A,ACE1 Angiotensin Converting Enzyme 1,Angiotensin I Converting Enzyme,Carboxypeptidase I, Dipeptidyl,Peptidyl Dipeptidase A
D009842	Oligopeptides	Peptides composed of between two and twelve amino acids.	Oligopeptide
D012015	Reference Standards	A basis of value established for the measure of quantity, weight, extent or quality, e.g. weight standards, standard solutions, methods, techniques, and procedures used in diagnosis and therapy.	Standard Preparations,Standards, Reference,Preparations, Standard,Standardization,Standards,Preparation, Standard,Reference Standard,Standard Preparation,Standard, Reference
D002851	Chromatography, High Pressure Liquid	Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.	Chromatography, High Performance Liquid,Chromatography, High Speed Liquid,Chromatography, Liquid, High Pressure,HPLC,High Performance Liquid Chromatography,High-Performance Liquid Chromatography,UPLC,Ultra Performance Liquid Chromatography,Chromatography, High-Performance Liquid,High-Performance Liquid Chromatographies,Liquid Chromatography, High-Performance
D003124	Colorimetry	Any technique by which an unknown color is evaluated in terms of standard colors. The technique may be visual, photoelectric, or indirect by means of spectrophotometry. It is used in chemistry and physics. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
D006626	Hippurates	Salts and esters of hippuric acid.
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man