Organelle membranes from germinating castro bean endosperm

Journal Article · Thu Jan 01 04:00:00 EST 1981 · Plant Physiol.; (United States)

OSTI ID:6643267

Donaldson, R P ^[1]; Tully, R E; Young, O A; Beevers, H

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1. George Washington Univ., Washington, DC

Glyoxysome ghosts were isolated from germinating castor bean endosperms using established methods. Electron microscopic examination showed that some matrix material was retained within the glyoxysomal membrane. Two cytochrome reductases and phosphorylcholine glyceride transferase co-sedimented with the alkaline lipase, a known component of the glyoxysome membrane, in sucrose gradient centrifugation of osmotically shocked glyoxysomes. The activities of these enzymes in the glyoxysome membranes were compared to those in the endoplasmic reticulum relative to phospholipid content. On this basis, the phosphorylcholine glyceride transferase was 10-fold more active in the endoplasmic reticulum, whereas the lipase was 50-fold more active in the glyoxysome membrane. The cytochrome reductases were only 2-fold more active in the endoplasmic reticulum, indicating that they are components of the two membranes. Difference spectroscopy of the glyoxysome membrane suspension revealed the presence of a b5-type cytochrome similar to that found in the endoplasmic reticulum. Since the glyoxysome membrane is apparently derived from the endoplasmic reticulum, components of the endoplasmic reticulum such as these are likely to be incorporated into the glyoxysome membrane during biogenesis. Enzyme activites involving the cofactors NADH or CoA were measurable in broken, but not in intact, glyoxysomes. Thus, it appears that cofactors for enzymes within the organelle cannot pass through the membrane.

• DOE Contract Number: EY-76-S-03-0034
• OSTI ID: 6643267
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 67:1; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550200 -- Biochemistry
550800* -- Morphology
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
CASTOR
CELL CONSTITUENTS
CELL MEMBRANES
CENTRIFUGATION
COENZYMES
COMPARATIVE EVALUATIONS
CYTOCHROMES
DATA
ELECTRON MICROSCOPY
ENDOSPERM
ENZYME ACTIVITY
ENZYMES
INFORMATION
KINETICS
MEDICINAL PLANTS
MEMBRANES
METABOLITES
MICROSCOPY
NAD
NADP
NUCLEOTIDES
ORGANIC COMPOUNDS
PIGMENTS
PLANT TISSUES
PLANTS
PROTEINS
REACTION KINETICS
REDOX PROCESS
REPROCESSING
SEEDS
SEPARATION PROCESSES
STRUCTURAL CHEMICAL ANALYSIS