Lipase activities in castor bean endosperm during germinaion. [Ricinus communis; glyoxysomes]

Journal Article · Tue Jan 01 04:00:00 EST 1974 · Plant Physiol.; (United States)

OSTI ID:7358702

Muto, S; Beevers, H

Two lipases were found in extracts from castor bean (Ricinus communis L.) endosperm. One, with optimal activity at pH 5.0 (acid lipase), was present in dry seeds and displayed high activity during the first 2 days of germination. The second, with an alkaline pH optimum (alkaline lipase), was particularly active during days 3 to 5. When total homogenates of endosperm were fractionated into fat layer, supernatant, and particulate fractions, the acid lipase was recovered in the fat layer, and the alkaline lipase was located primarily in the particulate fraction. Sucrose density gradient centrifugation showed that the alkaline lipase was located mainly in glyoxysomes, with some 30 percent of the activity in the endoplasmic reticulum. When glyoxysomes were broken by osmotic shock and exposed to KCl, which solubilizes most of the enzymes, the alkaline lipase remained particulate and was recovered with the glyoxysomal ''ghosts'' at equilibrium density 1.21 g/cm/sup 3/ on the sucrose gradient. Association of the lipase with the glyoxysomal membrane was supported by the responses to detergents and to butanol. The alkaline lipase hydrolyzed only monosubstituted glycerols. The roles of the two lipases in lipid utilization during germination of castor bean are discussed.

• Research Organization: Univ. of California, Santa Cruz
• OSTI ID: 7358702
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 54; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
550300 -- Cytology
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BIOLOGY
BIOMASS
CASTOR
CELL CONSTITUENTS
CHEMISTRY
CYTOLOGY
ENDOPLASMIC RETICULUM
ENDOSPERM
ENERGY SOURCES
ENZYMES
ESTERASES
GERMINATION
HYDROLASES
KINETICS
LIPASES
MEDICINAL PLANTS
METABOLISM
ORGANOIDS
PLANT TISSUES
PLANTS
REACTION KINETICS
RENEWABLE ENERGY SOURCES