Isolation and characterization of an insulin-degrading enzyme from Drosophila melanogaster
An insulin-degrading enzyme (IDE) from the cytoplasm of Drosophila Kc cells has been purified and characterized. The purified enzyme is a monomer with an s value of 7.2 S, an apparent K/sub m/ for porcine insulin of 3 ..mu..M, and a specific activity of 3.3 nmol of porcine insulin degraded/(min x mg). N-Terminal sequence analysis of the gel-purified enzyme gave a single, serine-rich sequence. The Drosophila IDE shares a number of properties in common with its mammalian counterpart. The enzyme could be specifically affinity-labeled with (/sup 125/I)insulin, has a molecular weight of 110K, and has a pI of 5.3. Although Drosophila Kc cells grow at room temperature, the optimal enzyme activity assay conditions parallel those of the mammalian IDE: 37/sup 0/C and a pH range of 7-8. The Drosophila IDE activity, like the mammalian enzymes, is inhibited by bacitracin and sulfhydryl-specific reagents. Similarly, the Drosophila IDE activity is insensitive to glutathione as well as protease inhibitors such as aprotinin and leupeptin. Insulin-like growth factor II, equine insulin, and porcine insulin compete for degradation of (/sup 125/I)insulin at comparable concentrations (approximately 10/sup -6/ M), whereas insulin-like growth factor I and the individual A and B chains of insulin are less effective. The high degree of evolutionary conservation between the Drosophila and mammalian IDE suggest an important role for this enzyme in the metabolism of insulin and also provides further evidence for the existence of a complete insulin-like system in invertebrate organisms such as Drosophila.
- Research Organization:
- Massachusetts Institute of Technology, Cambridge (USA)
- OSTI ID:
- 7164507
- Journal Information:
- Biochemistry; (United States), Vol. 27:12
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
ENZYMES
AUTORADIOGRAPHY
MOLECULAR STRUCTURE
PURIFICATION
INSULIN
BIODEGRADATION
AMINO ACID SEQUENCE
BIOLOGICAL EVOLUTION
DROSOPHILA
ELECTROPHORESIS
IODINE 125
SERINE
AMINO ACIDS
ANIMALS
ARTHROPODS
BETA DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DECOMPOSITION
DIPTERA
ELECTRON CAPTURE RADIOISOTOPES
FLIES
FRUIT FLIES
HORMONES
HYDROXY ACIDS
INSECTS
INTERMEDIATE MASS NUCLEI
INVERTEBRATES
IODINE ISOTOPES
ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDE HORMONES
RADIOISOTOPES
550201* - Biochemistry- Tracer Techniques
550601 - Medicine- Unsealed Radionuclides in Diagnostics