Stereospecific distribution of fatty acids in bovine milk fat triglycerides

Parodi, Peter W.

doi:10.1017/s0022029900016873

Cited by 54 publications

(45 citation statements)

References 20 publications

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“…Raschke et al (6) observed from methylation studies that mnn2 mannoprotein still contained a small amount of 1--2-linked mannose and Nakajima and Ballou (20) was concluded that this activity might be involved in synthesis of the core rather than the outer chain. Subsequently, it has been shown that membranes prepared from the mnn2 mutant make endogenous mannan with properties of the wild-type polymer (21) and that the same membranes catalyze formation of products with exogenous acceptors that are -similar to those obtained with membranes from wild-type strains (22). Thus, it appears that the S. cerevisiae mnn2 mutant, like the mnn2-2 mutant of Kluyveromyces lactis (23), has a defect that prevents expression of an enzyme activity in the intact cell even though the glycosyltransferase activity is demonstrable in cell extracts.…”

Section: Discussionmentioning

confidence: 99%

Yeast invertase polymorphism is correlated with variable states of oligosaccharide chain phosphorylation.

Frevert¹,

Ballou²

1982

Proc. Natl. Acad. Sci. U.S.A.

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Saccharomyces cerevisiae invertase (EC 3.2.1.26) isolated from wild-type strain X2180 can be resolved by isoelectric focusing into at least seven bands revealed by. anactivity stain. Most of this polymorphism is eliminated in mutants that are defective in phosphorylation of the mannoprotein carbohydrate chains (mnn4 and mnn6). In contrast to strain X2180, invertase from the mnn9 mutant, which makes mannoprotein lacking the outer portion of the polymannose chains, shows only two major bands on isoelectric focusing. Although mnn2 mannoprotein is thought not to have any branches in its outer chain, the invertase of this mutant shows at least six bands on isoelectric focusing, and digestion of this invertase with an endo-al---*6-mannanase. that removes the unbranched outer chain produces an invertase with two bands that are similar to those from the mnn9 mutant. The invertase from mnn2 cells, grown with [32P]orthophosphate and precipitated.with specific antiserum, gives at least five radioactive bands on isoelectric focusing, and after digestion with the endomannanase the radioactivity no longer migrates with the residual invertase. Mutants with shortened and unbranched outer chains (mnn2 mrnn7, mnn2 mnn8, and mnn2 mnnlO) give invertase patterns similar to mnn2. The results suggest that multiple states of outer chain phosphorylation lead to isoelectric polymorphism of S. cerevsiae external invertase and, because invertase has nine carbohydrate chains, no more than one phosphate group per chain would be required to account for this property. Methods. Except for the radioactive labeling experiment, protoplast digests were prepared according to Schwenke and Nagy (12). After mercaptoethanol treatment, cells were incubated with Zymolyase (1.5 mg/ml) for 1 hr, the digest was centrifuged at 2,000 x g for 10. min, and the supernatant solution was dialyzed for 20 hr against distilled water and then concentrated 10-fold by Iyophilization. Cultures ofmnn2, mnn2 mnn9, and. wild-type cells were grown on Wickerham's minimal medium (13) to mid-logarithmic phase. A suitable portion of each culture was centrifuged and resuspended in 2 ml of a minimal medium, in which sulfate and phosphate salts were replaced by chloride salts, such that ODwo = 2. After growth for 4 hr at 30'C, the cultures were centrifuged and the cells were suspended in 2 ml of a medium for induction and labeling of invertase that contained 50 mM ammonium sulfate, 0.1% D-glucose, 0.1 mM potassium phosphate, 3 mCi of H332PO4, and 1 mCi of H235SO4 (1 Ci = 3.7 x 1010 becquerels). During a 1-hr incubation, invertase was induced, after which the cells were lysed by addition of 50 units of lyticase in 200 Al of 1.4 M sorbitol that was 5 mM in NaN3, 2.5 mM in MgCl2, and 40 mM in mercaptoethanol. After incubation for 30 min at 30'C, the protoplasts and insoluble material were removed by centrifugation, and 15 1.5 of anti-invertase serum was added. After a 2-hr incubation, 100 /l of Staph. aureus cells in 0.5%.Triton X-100 was added, and 30 min later the cells we...

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Section: Discussionmentioning

confidence: 99%

Yeast invertase polymorphism is correlated with variable states of oligosaccharide chain phosphorylation.

Frevert¹,

Ballou²

1982

Proc. Natl. Acad. Sci. U.S.A.

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“…There are two reasons for this. First, short-chain fatty acids are usually located on the sn-3 position in the triacylglycerols (11,12). Due to reduced steric hindrance, these moieties will be more susceptible to hydrolysis during the processing of the milk fats or during burial.…”

mentioning

confidence: 99%

Direct chemical evidence for widespread dairying in prehistoric Britain

Copley

Berstan

Dudd

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

429

414

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Domesticated animals formed an important element of farming practices in prehistoric Britain, a fact revealed through the quantity and variety of animal bone typically found at archaeological sites. However, it is not known whether the ruminant animals were raised purely for their tissues (e.g., meat) or alternatively were exploited principally for their milk. Absorbed organic residues from pottery from 14 British prehistoric sites were investigated for evidence of the processing of dairy products. Our ability to detect dairy fats rests on the observation that the ␦ 13 C values of the C18:0 fatty acids in ruminant dairy fats are Ϸ2.3‰ lower than in ruminant adipose fats. This difference can be ascribed to (i) the inability of the mammary gland to biosynthesize C 18:0; (ii) the biohydrogenation of dietary unsaturated fatty acids in the rumen; and (iii) differences (i.e., 8.1‰) in the ␦ 13 C values of the plant dietary fatty acids and carbohydrates. The lipids from a total of 958 archaeological pottery vessels were extracted, and the compound-specific ␦ 13 C values of preserved fatty acids (C16:0 and C18:0) were determined via gas chromatography-combustion-isotope ratio mass spectrometry. The results provide direct evidence for the exploitation of domesticated ruminant animals for dairy products at all Neolithic, Bronze Age, and Iron Age settlements in Britain. Most significantly, studies of pottery from a range of key early Neolithic sites confirmed that dairying was a widespread activity in this period and therefore probably well developed when farming was introduced into Britain in the fifth millennium B.C. There is little doubt that domesticated cattle, sheep, goats, and pigs were an integral part of early Neolithic farming in Britain. However, difficulties in establishing whether they were exploited for dairy products, wool, and traction, the so-called ''secondary products'' (1), has proved to be a major hurdle in our understanding of the evolution of prehistoric economies. The recognition by early farmers that animals could be reared for their milk would have had major impacts on diet, health, and subsistence economy (2). As such, it is of great archaeological and scientific interest to determine how these domesticates were utilized in antiquity: were they valued primarily as a meat source, were they exploited for their ''secondary products'' such as milk, or were different economic strategies used to maximize the production of both commodities? Evidence for dairying in prehistory is currently limited to certain specialist vessels, e.g., putative cheese strainers (3), and evidence from faunal remains of herds that are suggestive of dairying (4, 5). However, direct chemical evidence for widespread dairying at prehistoric sites anywhere in the world is currently lacking.Degraded animal fats, recognized by the high abundances of n-hexadecanoic (C 16:0 ) and n-octadecanoic (C 18:0 ) acids, are preserved widely within archaeological pottery, particularly those vessels involved in the preparation, consumption, and...

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“…However, for purposes of fitting experimental data, the region of operation with which we are concerned is that of Adapted from Parodi (1979). c Estimate of the initial concentration of accessible fatty acid residues:…”

Section: Reactor Performancementioning

confidence: 99%

“…Calf pregastric esterase is a sn-1,3-specific lipase; therefore, only the fatty acid residues at these positions are accessible to the enzyme. In order to estimate [G j ] o , the saponification data were combined with data collected by Parodi (1979) concerning the stereospecific distribution of each fatty acid species in milk fat (see Table II). The F-ratio is the extra mean sum of squares divided by the mean sum of squares of the full model.…”

Section: Determination Of Initial Concentration Of Accessible Glycerimentioning

confidence: 99%

Effect of pH on the production of lipolyzed butter oil by a calf pregastric esterase immobilized in a hollow-fiber reactor: II. Multiresponse kinetics

Lessard

Hill

2000

Biotechnol. Bioeng.

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Stereospecific distribution of fatty acids in bovine milk fat triglycerides

Cited by 54 publications

References 20 publications

Yeast invertase polymorphism is correlated with variable states of oligosaccharide chain phosphorylation.

Yeast invertase polymorphism is correlated with variable states of oligosaccharide chain phosphorylation.

Direct chemical evidence for widespread dairying in prehistoric Britain

Effect of pH on the production of lipolyzed butter oil by a calf pregastric esterase immobilized in a hollow-fiber reactor: II. Multiresponse kinetics

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