Reversible independent unfolding of the domains of urokinase monitored by sup 1 H NMR

Human urinary-type plasminogen activator (urokinase) and proteolytic fragments corresponding to the kringle, EGF-kringle, and protease domains have been examined by {sup 1}H NMR spectroscopy. The intact protein shows a very well-resolved spectrum for a molecule of this size (MW 54,000), with resonan...

Full description

Saved in:
Bibliographic Details
Published in:Biochemistry (Easton) 1989-08, Vol.28:16
Main Authors: Bogusky, M.J., Dobson, C.M., Smith, R.A.G.
Format: Article
Language:English
Subjects:
550201 - Biochemistry- Tracer Techniques
ANIMALS
BARYONS
BASIC BIOLOGICAL SCIENCES
CHEMICAL BONDS
CONFORMATIONAL CHANGES
DRUGS
ELEMENTARY PARTICLES
ENZYMES
FERMIONS
FIBRINOLYTIC AGENTS
GROWTH FACTORS
HADRONS
HEMATOLOGIC AGENTS
HYDROLASES
MAGNETIC RESONANCE
MAMMALS
MAN
MITOGENS
MOLECULAR STRUCTURE
NONSPECIFIC PEPTIDASES
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
PH VALUE
PLASMINOGEN
PRIMATES
PROTEINS
PROTONS
RESONANCE
TEMPERATURE EFFECTS
UROKINASE
VERTEBRATES
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Human urinary-type plasminogen activator (urokinase) and proteolytic fragments corresponding to the kringle, EGF-kringle, and protease domains have been examined by {sup 1}H NMR spectroscopy. The intact protein shows a very well-resolved spectrum for a molecule of this size (MW 54,000), with resonance line widths not greatly increased from those of the isolated domains. On increasing the temperature, the protein at pH values close to 4 was found to undergo two distinct and reversible conformational transitions. These were identified, by comparison with spectra of the proteolytic fragments, as the unfolding of the kringle (and EGF) domains (at {approximately} 42{degree}C) and of a segment of the protease domain (at {approximately} 60{degree}C). The remaining segment of the protease domain showed persistent structure to at least 85{degree}C at pH 4; only at lower pH values could complete unfolding be achieved. The results indicate that the structures and stabilities of the isolated domains are closely similar to those in the intact protein and suggest that there is a degree of independent motion at least between the kringle and protease domains.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00442a028