A new radiochemical method to determine the stability constants of metal chelates attached to a protein

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Journal of Nuclear Medicine; (USA)

OSTI ID:6976266

Subramanian, K M; Wolf, W ^[1]

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1. Univ. of Southern California, Los Angeles (USA)

A new method was developed to determine the stability constants of bifunctional chelates of indium (In) coupled to a protein. This method utilizes the displacement reaction between an indium complex and ferric ion. By measuring the position equilibrium constant 'K' of this reaction and knowing the stability constant of the corresponding ferric chelate, the overall formation constant of the indium chelate can be determined. Human serum albumin (HSA) was conjugated with ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) using their cyclic dianhydrides. A new method was developed to couple triethylenetetraminehexaacetic acid (TTHA) with HSA using Woodward's Reagent K. The chelating agents coupled to HSA were complexed with indium-114m-(114mIn) labeled indium and purified by dialysis or microcentrifugation. The stability constants of these indium complexes were determined at physiologic pH using ferric chelate of nitrilotriacetic acid (Fe-NTA) as the source of ferric ion. No significant differences were found between the stability constants of the indium chelates conjugated to protein and those of unconjugated species.

• OSTI ID: 6976266
• Journal Information: Journal of Nuclear Medicine; (USA), Journal Name: Journal of Nuclear Medicine; (USA) Vol. 31:4; ISSN 0161-5505; ISSN JNMEA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ALBUMINS
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CHELATING AGENTS
DAYS LIVING RADIOISOTOPES
DRUGS
DTPA
EDTA
ELECTRON CAPTURE RADIOISOTOPES
INDIUM 114
INDIUM ISOTOPES
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC
ISOMERIC NUCLEI
ISOTOPES
LABELLED COMPOUNDS
MAMMALS
MAN
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PRIMATES
PROTEINS
RADIOISOTOPES
RADIOPHARMACEUTICALS
RADIOPROTECTIVE SUBSTANCES
STABILITY
VERTEBRATES