Penetration and fusion of phospholipid vesicles by lysozyme

Journal Article · Sun Oct 01 04:00:00 EDT 1989 · Archives of Biochemistry and Biophysics; (USA)

DOI:https://doi.org/10.1016/0003-9861(89)90420-7· OSTI ID:5364337

Kim, J; Kim, H ^[1]

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1. Korea Advanced Institute of Science and Technology, Seoul

The lysozyme-induced fusion of phosphatidylserine/phosphatidylethanolamine vesicles as studied at a wide range of pH is found to correlate well with the binding of this protein to the vesicles. An identical 6000 molecular weight segment of lysozyme at the N-terminal region is found to be protected from tryptic digestion when initially incubated with vesicles at several pH values. Only this segment is labeled by dansyl chloride, which is partitioned into the bilayer. These results suggest the penetration of one segment of lysozyme into the bilayer. Photoactivated labeling of the membrane-penetrating segment of lysozyme with 3-(trifluoromethyl)-3-(({sup 125}I)iodophenyl)diazirine (({sup 125}I)TID) and subsequent identification of the labeled residues by Edman degradation and gamma-ray counting indicate that four amino acids from the N-terminal are located outside the hydrophobic core of the bilayer. Although treatment of the membrane-embedded segment with aminopeptidase failed to cleave any amino acids from the N-terminal, it appears that a loop of lysozyme segment near the N-terminal penetrates into the bilayer at acidic pH. A helical wheel diagram shows that the labeling is done mainly on one surface of the alpha-helix. The penetration kinetics as studied by time-dependent ({sup 125}I)TID labeling coincide with the fusion kinetics, strongly suggesting that the penetration of the lysozyme segment into the vesicles is the cause of the fusion.

• OSTI ID: 5364337
• Journal Information: Archives of Biochemistry and Biophysics; (USA), Journal Name: Archives of Biochemistry and Biophysics; (USA) Vol. 274:1; ISSN ABBIA; ISSN 0003-9861
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACID SEQUENCE
AMINO ACIDS
AMINOPEPTIDASES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
ESTERS
GLYCOSYL HYDROLASES
HYDROLASES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIPIDS
LYSOZYME
MOLECULAR BIOLOGY
MOLECULAR STRUCTURE
MOLECULAR WEIGHT
NUCLEI
O-GLYCOSYL HYDROLASES
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PEPTIDE HYDROLASES
PHOSPHOLIPIDS
RADIOISOTOPES
REACTION KINETICS
SERINE PROTEINASES
TRACER TECHNIQUES
TRYPSIN