Isolated milk fat globules as substrate for lipoprotein lipase: study of factors relevant to spontaneous lipolysis in milk
Fat globules isolated from normal and from spontaneous milk samples were compared as substrates for purified lipoprotein lipase. Only slight differences were observed. Fat globules isolated from fresh warm milk were almost resistant to lipolysis. This included globules from milk prone to spontaneous lipolysis. Cooling made the globules accessible to rapid lipolysis even if they were from normal milk. Rewarming the fat globules did not reverse the process. Maximum rate of lipolysis (after rewarming) required fat globules be stored at 10/sup 0/C or below for 5 to 10 h. Lipolysis at 4/sup 0/C usually started after a lag time of 3 to 5 h, but with fat globules from spontaneous milk the lag time was shorter. Fat globules isolated from cold milk were a poor substrate at 4/sup 0/C but were lipolyzed when warmed. When /sup 125/I-labeled lipase was added to fresh warm milk, some of the lipase bound to the milk fat globules but it caused little lipolysis. Binding increased after cooling, as did lipolysis. Both binding of lipase and lipolysis were impeded by the presence of skim milk. Another way to make fat globules isolated from fresh warm milk susceptible to lipolysis was to treat them with chemicals known to remove proteins.
- Research Organization:
- Agricultural Univ. of Norway, As-NLH
- OSTI ID:
- 6550914
- Journal Information:
- J. Dairy Sci.; (United States), Vol. 70:3
- Country of Publication:
- United States
- Language:
- English
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BUTTER FAT
METABOLISM
LIPASE
BIOCHEMICAL REACTION KINETICS
RECEPTORS
IODINE 125
LIPOPROTEINS
MILK
SUBSTRATES
TRACER TECHNIQUES
BETA DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BODY FLUIDS
CARBOXYLESTERASES
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
ESTERASES
ESTERS
FATS
FOOD
HYDROLASES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIPIDS
MATERIALS
MEMBRANE PROTEINS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
TRIGLYCERIDES
550201* - Biochemistry- Tracer Techniques
550501 - Metabolism- Tracer Techniques