Compositional and electrophoretic changes in buffalo milk-fat globule membrane proteins during lactation

Abstract

Chemical analyses, polyacrylamide-gel electrophoresis and isoelectric focusing of milk-fat globule membrane proteins (FGMP) obtained from the milk of 2 Murrah buffaloes were done to determine if any change in composition occurred during lactation. Changes in the levels of sialic acid, hexose, hexosamine, N and P were found in the FGMP obtained at different stages of lactation. On the day of parturition, 8 major proteins in FGMP were determined by sodium dodecyl sulphate polyacrylamide-gel electrophoresis whereas 6 major proteins were obtained in FGMP of middle and late lactation milks. Isoelectric focusing of FGMP showed 8-9, 9-13 and 13-16 proteins from colostrum, middle and late lactation milks, respectively and the isoelectric pH of the proteins varied from 5-25 to 7-80, 5-85 to 8-30 and 5-75 to 8*61 respectively.

Separation of the Proteins of Bovine Milk‐Fat‐Globule Membrane by Electrofocusing with Retention of Enzymatic and Immunological Activity

“…Analytical procedures for the separation of fatglobule-membrane proteins are currently restricted to electrophoresis in polyacrylamide gels containing dodecyl sulphate [lo-12, 14,16, 351 or in agarose gels 1271 or electrofocusing under denaturing conditions [13,15]. While these methods have provided useful information on the nature of fat-globule-membrane proteins, they provide only small quantities of purified protein for further analysis and, in many cases, lead to protein denaturation.…”

Composition, Properties and Nutritional Aspects of Milk Fat Globule Membrane – A Review

“…For instance, fat globules from the milk of Jersey cows (average size approximately 4.5 µm) are normally larger than fat globules from the milk of Friesian cows (average size approximately 3.5 µm), although there are also considerable variations between cows of the same breed. There is a decrease in the average fat globule size as lactation progresses [Singh, 2006].…”

“…A typical isolation method can be divided into four steps [Mather, 2000;Singh, 2006]: fat globule separation, cream washing, release of MFGM from the globules and collection of the MFGM material. First, cream can be separated from milk by a laboratory centrifuge or in a large scale, bench-top cream separator.…”

“…Future experiments would require a controlled feeding regime, as factors other than stage of lactation, such as feed (the quality of which can be season dependent), may have confounded the results obtained in previous studies. Furthermore, the results of the study on buffalo milk suggest that mammary gland development plays a significant role [Singh & Ganguli, 1976], particularly in the days immediately post partum. On the basis of the fact that large compositional changes occur in the first few days post partum [Anderson & Cheeseman, 1975], it is postulated that significant changes in fat globule stability take place during this period.…”

“…From a nutritional prospective, it has been previously shown that some fractions of the MFGM may be shed into the skim milk [Singh, 2006] and spontaneously assemble into liposomes, or those liposomes might be artificially formed due to homogenization. Through disruption of the native macrostructure by homogenization, some bioactivities or at least bioactive molecules might be carried over to the skim milk.…”