Hydrolysis of the amidine analogs of penicillins

The products of the hydrolytic degradation of 6-beta-(hexahydro-IH-azepenyl-1)methylenamino) penicillanic acid, 6-beta-(N,N-dimethylformamidino-N1)-penicillanic acid and 6-beta-(morpholinyl-1)methylenamino penicillanic acid were identified with the method of thin-layer chromatography and paper electrophoresis in neutral, acid and alkaline solutions and in the presence of penicillinase. The data of the study showed that acid hydrolysis of the amidine analogues of penicillins resulted in cleavage of the beta-lactame cycle and formation of the respective penicillanic acids. In the alkaline medium the secondary amine (hexamethylenimine, dimethylamine, morpholine) was cleaved from the antibiotic side chain and the resulting N-formyl-6-aminopenicillanic acid was further cleaved up to peniciec acid. The beta-lactame cycle of the antibiotics was cleaved under the effect of penicillinase and the resulting penicilloinic acids degraded into peniciec acid, N-formylpeniciec acid and secondary amines. In the nutral solution the antibiotics were transformed into N-formyl-6-aminopenicillanic acid and penicilloinic acids at the first stage of the hydrolysis followed by their further degradation with formation of N-formylpeniciec acid, peniciec acid and secondary amines.     

Electrochemical bromination of cholest-5-enes

Four 5,6-unsaturated steroids--3beta-chlorocholest-5-ene (1a), cholesterol (1b) and its acetate (1c) and benzoate (1d)-were subjected to constant current electrolysis (50 mA, 2 F mol(-1)) in an electrolytic cell divided by a ceramic membrane, using a platinum foil as the anode and a graphite stick as the cathode. When electrolysis was carried out in a solution of tetraethylammonium bromide in aprotic solvents (dichloromethane, acetonitrile or acetic anhydride), the addition of electrochemically-generated elemental bromine onto the double bond of the cholesterol derivatives gave their corresponding 5alpha,6beta-dibromosteroids--3beta-chloro-5alpha,6beta-dibromocholestane (2a), 5alpha,6beta-dibromocholestan-3beta-ol (2b), 5alpha,6beta-dibromocholestan-3beta-yl acetate (2c) and 5alpha,6beta-dibromocholestan-3beta-yl benzoate (2d)--as the sole products, and in good yields (58-91%). However, the electrolysis of steroids 1a-c in a solution of tetraethylammonium bromide with methanol as the solvent proceeded to give, in addition to dibromides 2a-c, the corresponding diastereomeric pairs of 5-bromo-6-methoxysteroids: 5alpha-bromo-3beta-chloro-6beta-methoxycholestane (3a) and 5beta-bromo-3beta-chloro-6alpha-methoxycholestane (4a), 5alpha-bromo-6beta-methoxycholestan-3beta-ol (3b) and 5beta-bromo-6alpha-methoxycholestan-3beta-ol (4b) and 5alpha-bromo-6beta-methoxycholestan-3beta-yl acetate (3c) and 5alpha-bromo-6beta-methoxycholestan-3beta-yl acetate (4c). The benzoate 1d was not soluble enough in methanol, even with heating. The products were characterized by physical and spectral data (IR, 1H NMR and 13C NMR). Single crystal X-ray structure determinations of compounds 2a and 3a are also reported.     

Stability of 6-beta-[(hexahydro-1H-azepin-l-yl)methyleneamino]-penicillanic acid in aqueous solutions]

Stability of acqueous solutions of 6-beta-[(hexahydro-IH-azepin-I-yl)methylenamino] penicillanic acid at various values of pH and temperature was studied. It was found that inactivation of the antibiotic in both the acid and the alkaline medium proceeded according to the equation of the 1st order. At pH 1.3 and a temperature of 35 degrees the half life of the antibiotic was 7 hours. The activation energy calculated according to the Arrenius equation was 13.5 kcal/mol at pH 1.3 and 22.2 kcal/mol at pH 10.5. The antibiotic was inactivated in glycol and phosphate buffers. Its qualitative analysis was performed according to an improved iodometric method.     

Penicillanic acid sulfone: nature of irreversible inactivation of RTEM beta-lactamase from Escherichia coli

When penicillanic acid sulfone in large molar excess is incubated with the RTEM beta-lactamase, the enzyme becomes inactivated irreversibly. From studies of the consequential spectroscopic changes, from the use of specifically tritiated penicillanic acid sulfone, and from comparison by isoelectric focusing of the enzyme after inactivation by the sulfone and by clavulanic acid, the inactivated enzyme appears to be cross-linked by a beta-aminoacrylate fragment deriving from C-5, C-6, and C-7 of the original beta-lactam. Model studies on the behavior of alcoholic solutions of penicillanic acid sulfone in the presence of amines are entirely consistent with this interpretation.     

Synthesis and β-lactamase inhibitory activity of 6-fluoropenicillanic acids

The benzyl 6-fluoro-penicillanate sulfides 4a, 6a, 7a; and sulfones 6c, 7d were synthesized. The conversion to their free acids 4b, 4b, 6d, 7b, 7e and potassium salts 7c, 7f are described. These acids and salt 7c were evaluated as β- lactamase inhibitors using β-lactamase I from Bacillus cereus. The data indicate that substitution of the 6-hydrogen by a 6- fluorine atom on 6β-bromopenicillanic acid (1), leads to loss of β-lactamase inhibitory activity. In the case of the isomers 6β- and 6-fluoropenicillanic acids the 6β-enantiomer proved to be considerably more potent. Potassium salts of 6β- fluoropenicillanate sulfide and sulfone were unstable in solid state and in water solution. The fragmentation of the sulfone in two parts in water solution is consistent with the hydrolytic behavior of the penicillanic acid sulfone (2) with 0.5 N NaOH.     

Steroidal 21-diazo ketones: photogenerated corticosteroid receptor labels.

The 21-diazo derivatives of 9 alpha-fluoro- and 9 alpha-bromo-21 deoxycorticosterone, 21-deoxycorticosterone, and progesterone were synthesized for use as photoaffinity labels for corticosteroid receptors. In the isolated toad bladder system, 9 alpha-bromo-21-diazo-21-deoxycorticosterone was as active as d-aldosterone and more active than 9 alpha-fluoro-cortisol in augmenting active Na+ transport. The activities of 21-diazoprogesterone and progesterone were equal; both were much less potent than d-aldosterone, however. These results indicate that the 21-diazo derivatives had significant functional activity in the toad bladder system. The rat kidney slice system was used to estimate the relative affinities of the diazo steroids for aldosterone receptor sites by competition experiments. At 100-fold excess of competitor to [3-H]aldosterone, the order of affinities was 9 alpha-fluoro-21-diazo-21-deoxycorticosterone greater than 9 alpha-bromo-21-diazo-21-deoxycorticosterone greater than 21-diazoprogesterone. Moreover, 9 alpha-bromo-21-diazo-21-deoxycorticosterone reduced binding of [3-H]aldosterone to cytoplasmic and nuclear forms of the receptor proportionately. On the basis of competition for [3-H]corticosterone binding, presumably to corticosteroid-binding globulin (CBG), the order of affinities was 21-diazo-21-deoxycorticosterone greater than 21-diazoprogesterone greater than 9 alpha-bromo-21-diazo-21-deoxycorticosterone. These findings indicate that 21-diazo steroids may be suitable as photogenerated affinity labels for mineralocorticoid receptors. The tritiated derivative, [1,2-3-H]-9 alpha-bromo-21-diazo-21-deoxycorticosterone (specific activity 25 Ci/mol) was synthesized and used in model experiments on photogenerated covalent binding to rat plasma proteins. Irradiation with uv light resulted in binding of [1,2-3-H]-9 alpha-bromo-21-diazo-21-deoxycorticosterone to plasma proteins, that was resistant to extraction with methylene dichloride and did not exchange with unlabeled corticosterone. The diazocorticosteroids, therefore, may have the requisite functional and selectivity properties for photoaffinity labeling of corticosteroid-binding proteins. Further studies are needed, however, to assure that photogenerated labeling with these steroids was site specific.     

Kinetically controlled synthesis of ampicillin with immobilized penicillin acylase in the presence of organic cosolvents

Penicillin acylase (PA) is used in the industrial production of 6-amino penicillanic acid (6-APA). However, by proper control of reaction medium, the enzyme can be used in the reverse synthesis of β-lactam antibiotics from the corresponding β-lactam nuclei and suitable acyl donors. Under thermodynamically controlled strategy, the use of organic cosolvents can favor synthesis over hydrolysis by lowering water activity and favoring the non-ionic reactive species. Under kinetically controlled strategy using activated acyl donors, organic solvents can favor synthesis by depressing hydrolytic reactions. Results are presented on the synthesis of ampicillin from phenylglycine methyl ester and 6-APA with immobilized Escherichia coli PA in the presence of organic cosolvents. Several solvents were tested in terms of enzyme stability and solubility of substrates. Ethylene glycol, glycerol, 1–2 propanediol and 1–3 butanediol were selected accordingly and ampicillin synthesis was performed in all of them. Best results in terms of yield and productivity were obtained with ethylene glycol, with which further studies were conducted. Variables studied were enzyme to limiting substrate ratio, acyl acceptor to acyl donor ratio, organic solvent concentration, pH and temperature. Experimental design based on a two-level fractional factorial design was conducted. pH was determined as the most sensitive variable and was further optimized. The best conditions for ampicillin synthesis in terms of productivity, within the range of values studied for those variables, were pH 7.4, 28°C, 36 U_S PA/mmol 6-APA, 3 mol PGME/mol 6-APA and 45 % (v/v) ethylene glycol concentration. Productivity was 7.66 mM ampicillin/h, which corresponds to a specific productivity of 7.02 μmol ampicillin/h U_S at 55 % yield. Productivity was lower than in buffer but product yield was higher because of the much lower relative hydrolysis rates.     

Fatty acids bound to alpha-fetoprotein and albumin during rat development

The time-course levels and composition of the fatty acids bound to rat alpha-fetoprotein (AFP) and albumin from several sources, were determined throughout development, and related to the intake of lipids from milk and the compositional changes in brain and liver fatty acids. The major fatty acids bound to AFP were acids bound to AFP were polyunsaturated and mainly docosahexaenoic acid (22:6(n-3], either from fetal serum (23.1%) or whole fetuses (21.6%), whereas palmitic (34.1%) and oleic (29.9%) acids were the main acids bound to albumin from the same sources. Amniotic fluid AFP contained less fatty acids (0.8 mol/mol protein) than that of fetal serum (1.4 mol/mol protein), and especially noticeable was a reduced amount of 22:6 (9.6%). Both AFP-concanavalin A microforms showed identical fatty acid composition. Levels of 22:6 bound to AFP decreased quickly after birth until a minimum at 8-10 days, increasing moderately thereafter. This minimum is coincident in time with a maximal accumulation of this fatty acid by brain and a loss of 22:6 by liver. Except for colostrum, levels of 22:6 in milk lipids were low and fairly constant, but always greater than those of its precursor, linolenic acid (18:3 (n-3]. These results support a specialized role of AFP in the plasma transport and tissue delivery of polyunsaturated fatty acids, and mainly docosahexaenoic acid.     

Activity coefficients of antibiotics in aqueous NaCl solutions at 298.2 K

Data at 298.2 K for aqueous NaCl solutions containing either D-phenylglycin, D-(p-hydroxy)phenylglycine, 6-amino penicillanic acid (6-APA), amoxicillin or ampicillin, are reported. The mean ionic activity coefficients of NaCl were determined from measurements of the responses of a sodium and a chloride ion-selective electrode. The activity coefficients of the precursors or the antibiotics were calculated from the values of the mean ionic activity coefficients using the exact cross differential relation between them. The correlation of solubility data using the activity coefficients measured in this work shows the same puzzling results previously observed in systems containing amino acids.     

Endogenous fatty acids are covalently and noncovalently bound to interphotoreceptor retinoid-binding protein in the monkey retina

Interphotoreceptor retinoid-binding protein (IRBP) purified from monkey interphotoreceptor matrix contains relatively high concentrations of endogenous fatty acids, 6.51 mol/mol of protein. Sixty-five percent of the total fatty acid bound to IRBP was found to be noncovalently attached, with the remainder covalently bound. The fatty acids are not residual components of phospholipids or neutral lipids, as judged by microchemical methods. The major fatty acids bound to IRBP are: palmitic (35%), stearic (21%), palmitoleic (7%), oleic (29%), linoleic (6%) and docosahexaenoic acids (2%). These fatty acids account for about 90% of the total fatty acid bound to interphotoreceptor matrix proteins extracted with organic solvents. Thus, IRBP may function as an intercellular fatty acid carrier and may depend on the covalently bound fatty acids for anchoring in the outer leaflet of cell membranes.     

Structure-activity relationships amongst beta-lactamase inhibitors

Using a variety of beta-lactamases including those from Escherichia coli (TEM-1), Enterobacter cloacae P99 and Staphylococcus aureus the inhibition profiles (I50 values) were determined for various groups of compounds including penicillins, penicillanic acid derivatives (sulphone and beta-halo substitutions), olivanic acids and clavulanic acid derivatives including substituted ethers and amines. Some of the latter compounds had higher activity than clavulanic acid with and without preincubation of enzyme with inhibitor but they still had poor activity against the P99 enzyme. Improvements in activity against Class I cephalosporinases were obtained with some derivatives of clavulanic acid but this was usually achieved at the expense of activity against clavulanate susceptible beta-lactamases. The olivanic acids had the highest activity against the widest range of beta-lactamases.     

Isolation and characterization of human cervical-mucus glycoproteins.

Mucus glycoproteins (mucins) were extracted from human cervical pregnancy mucus by 6 M-guanidinium chloride in the presence of proteinase inhibitors. Purification was subsequently achieved by isopycnic density-gradient centrifugation in CsCl/ guanidinium chloride gradients. The purified macromolecules represented approx. 85% of the total and were devoid of nucleic acids and proteins, as judged by analytical density-gradient centrifugation, disc electrophoresis and u.v. spectroscopy. Sedimentation-velocity centrifugation revealed a single unimodal peak with S20,W 50.1S in 0.2M-NaCl and 37.0S in 6 M-guanidinium chloride. Molecular weights obtained by light-scattering were 9.7 X 10(6) and 5.9 X 10(6) in 0.2M-NaCl and 6 M-guanidinium chloride respectively. The chemical analyses were typical of those of epithelial mucins. The macromolecules contained approx. 20% (w/w) of protein, and 65% (w/w) was accounted for as carbohydrate. Serine and threonine constituted 32 mol/100 mol and proline 10 mol/100 mol of the amino acids. The major sugars found were N-acetylglucosamine (12.8%), N-acetylgalactosamine (9.7%), galactose (18.7%), sialic acid (15.0%) and fucose (7.5%).     

N-3 and n-6 fatty acids stimulate restitution by independent mechanisms in the IEC-6 model of intestinal wound healing

We have shown that intestinal epithelial restitution is stimulated by n-3 and n-6 fatty acids. The current studies were undertaken to elucidate the mechanistic pathway(s) involved in this fatty acid modulation of restitution. Inhibition of phospholipase A(2) and eicosanoid synthesis and its effect on fatty acid stimulation of cellular migration in confluent, wounded IEC-6 monolayers was examined. The production of prostaglandin E(2) and transforming growth factor beta(1) were also measured in fatty acid supplemented cultures. Inhibition of phospholipase A(2) attenuated the effect of fatty acid stimulation of restitution in both n-3 and n-6 supplemented cultures. The lipoxygenase inhibitor, nordihydorguaretic acid (2 &mgr;mol/L), had no effect on stimulation of migration by fatty acids. The cyclooxygenase inhibitor piroxicam (5 &mgr;mol/L) and cyclooxygenase-2 specific inhibitors dexamethasone (2 &mgr;mol/L) and NS-398 (10 &mgr;mol/L) all attenuated the fatty acid stimulation of migration by n-6 fatty acids but had no effect on n-3 stimulated restitution. Prostaglandin E(2) production in n-6 supplemented cultures was significantly greater than in control and n-3 supplemented cultures and was partially inhibited by dexamethasone and NS-398. Latent transforming growth factor beta(1) production in n-3 supplemented cultures was significantly higher than baseline and n-6 supplemented cultures. Docosapentaenoic acid supplementation significantly enhanced the restitution process and NS-398 treatment had no effect on this stimulation of cellular migration. The liberation of fatty acid from the sn-2 position of phospholipid appears to be necessary for both n-3 and n-6 fatty acid stimulation of restitution. N-6 fatty acid modulation of restitution appears to be mediated through the production of eicosanoid products, however, prostaglandin E(2) does not appear to be the sole prostanoid involved. N-3 supplementation elevates the production of latent transforming growth factor beta(1) and may be responsible for n-3 mediated stimulation of restitution. These results further emphasize that n-3 and n-6 fatty acids convey their effects through unique pathways.     

An integrated process for the production and biotransformation of penicillin.

The extraction of Penicillin G (PG) from the filtered cultivation medium of Penicillium chrysogenum and its conversion into 6-amino penicillanic acid (6-APA) and phenyl acetic acid (PhA) at pH 8 was performed in a 10 l kühni extractor during the production by means of penicillin-G-amidase immobilized in a liquid membrane carrier system (LM). 6-APA was enriched in LM, and the PhA returned to the cultivation medium. After electrocoalescence of LM, the 6-APA was converted into ampicillin with the same enzyme at pH 6, while the liquid membrane phase and enzyme were recycled and reused.     

The synthesis of methyl 3 alpha, 7 alpha-diacetoxy-11-oxo-5 beta-cholan-24-oate.

Reaction of methyl-3 alpha-7 alpha-diacetoxy-11 alpha-bromo-12-oxo-5 beta-cholan-24-oate with sodium borohydride in pyridine solution containing sodium acetate gave the corresponding 11 beta, 12 beta-epoxide in 65% yield. The epoxy-ring was opened with hydrobromic or hydroiodic acid to give the corresponding 12 alpha-halo-11 beta-alcohols, which were converted to the halo-ketones and finally to methyl 3 alpha,7 alpha-diacetoxy-11-oxo-5 beta-cholan-24-oate.     

壳聚糖载体的改性及其用于固定化漆酶的研究

利用有机酸改性壳聚糖,并用交联法制备酸化的壳聚糖载体,然后用改性壳聚糖载体固定漆酶。甲酸、乙酸改性壳聚糖的最适条件:壳聚糖与甲酸、乙酸的质量摩尔比(g/mol)分别为100∶1、100∶1.5,戊二醛的质量分数为1%,缓冲溶液的pH分别是4.4、5.0,反应时间为3h;壳聚糖与酒石酸、草酸的质量摩尔比(g/mol)分别为100∶0.5、100∶2,戊二醛的质量分数为2%,缓冲溶液的pH分别是3.6、4.2,反应时间为4.5h。不同有机酸改性的壳聚糖用于漆酶的固定,其酶活都有不同程度的提高,尤其用酒石酸改性的壳聚糖载体效果最好,其酶活提高了57%。     

Plasma fatty acids and [13C]linoleic acid metabolism in preterm infants fed a formula with medium-chain triglycerides

Most preterm infant formulas contain medium-chain triacylglycerols (MCT), but the effects of MCT on polyunsaturated fatty acid status and metabolism are controversial. Thus, we studied the effects of MCT on linoleic acid metabolism using stable isotopes. Enterally fed preterm infants were randomized to receive for 7 days 40% of fat as MCT (n = 10) or a formula without MCT (n = 9). At study day 5, infants received orally 2 mg/kg body weight of (13)C-labeled linoleic acid. Fatty acids in plasma lipid classes and (13)C enrichment of phospholipid fatty acids were measured and tracer oxidation was monitored. Compared with the control group, the MCT group showed lower breath (13)CO(2) and higher plasma triacylglycerol contents of octanoic acid, of decanoic acid, and of total long-chain polyunsaturated fatty acids (57.1 +/- 4.4 micro mol/l vs. 37.9 +/- 4.8 micro mol/l, P < 0.01). Concentrations of several polyunsaturated fatty acids in plasma phospholipids and non esterified fatty acids were higher in the MCT group. (13)C concentrations in phospholipid n-6 fatty acids indicated no difference in the relative conversion of linoleic to arachidonic acid. We conclude that oral MCT effectively reduce polyunsaturated fatty acid and long chain polyunsaturated fatty acid oxidation in preterm infants without compromising endogenous n-6 long chain polyunsaturated fatty acid synthesis.     

Influence of the nitrogen source on Saccharomyces cerevisiae anaerobic growth and product formation.

To prevent the loss of raw material in ethanol production by anaerobic yeast cultures, glycerol formation has to be reduced. In theory, this may be done by providing the yeast with amino acids, since the de novo cell synthesis of amino acids from glucose and ammonia gives rise to a surplus of NADH, which has to be reoxidized by the formation of glycerol. An industrial strain of Saccharomyces cerevisiae was cultivated in batch cultures with different nitrogen sources, i.e., ammonium salt, glutamic acid, and a mixture of amino acids, with 20 g of glucose per liter as the carbon and energy source. The effects of the nitrogen source on metabolite formation, growth, and cell composition were measured. The glycerol yields obtained with glutamic acid (0.17 mol/mol of glucose) or with the mixture of amino acids (0.10 mol/mol) as a nitrogen source were clearly lower than those for ammonium-grown cultures (0.21 mol/mol). In addition, the ethanol yield increased for growth on both glutamic acid (by 9%) and the mixture of amino acids (by 14%). Glutamic acid has a large influence on the formation of products; the production of, for example, alpha-ketoglutaric acid, succinic acid, and acetic acid, increased compared with their production with the other nitrogen sources. Cultures grown on amino acids have a higher specific growth rate (0.52 h-1) than cultures of both ammonium-grown (0.45 h-1) and glutamic acid-grown (0.33 h-1) cells. Although the product yields differed, similar compositions of the cells were attained. The NADH produced in the amino acid, RNA, and extracellular metabolite syntheses was calculated together with the corresponding glycerol formation. The lower-range values of the theoretically calculated yields of glycerol were in good agreement with the experimental yields, which may indicate that the regulation of metabolism succeeds in the most efficient balancing of the redox potential.     

高效液相色谱法测定必特螺旋霉素发酵液中有机酸

必特螺旋霉素是运用基因工程技术获得的工程茵产生的一组以异戊酰螺旋霉素为主要成分的多组分新型抗生素,其前体为乙酸、丙酸、丁酸和异戊酸等有机酸。本研究利用高效液相色谱法以0．01mol／L磷酸缓冲液（pH2．3）和甲醇为流动相,分别在反相C8（α-酮戊二酸、乙酸、柠檬酸、琥珀酸、丙酸）和C18（丁酸、异戊酸）柱上定量测定了必特螺旋霉素前体酸和三羧酸循环相关有机酸。所建立的测定方法的相对标准偏差为0．10％～0．42％,回收率为93．19％～102．08％。     

Fatty acid composition of the milk lipids of Nepalese women: correlation between fatty acid composition of serum phospholipids and melting point.

Milk was collected from 36 Nepalese women, 15 to 32 years of age, in order to investigate relationships between the proportions of intermediate chain-length (C10-C14) fatty acids and critical n-3 and n-6 polyunsaturated fatty acids in the milk lipids they were producing. Serum was also obtained from these lactating women and the fatty acid composition of their serum phospholipid fraction was determined and compared with that of the corresponding milk lipid fraction. Compared to women in technologically advanced parts of the world, the serum phospholipids of the Nepalese women contained nutritionally adequate proportions of linoleic acid (LA) (16.8%), alpha-linolenic acid (ALA) (0.53%), arachidonic acid (AA) (5.69%), and docosahexaenoic acid (DHA) (1.42%). However, although the milk lipids contained adequate proportions of ALA (1.81%), AA (0.43%), and DHA (0.23%), the lipids contained low to moderate percentages of LA (mean, 9.05%). Positive correlations were observed between the proportions of AA (P=0.001, r=0.50) and ALA (P=0.03, r=0.36) in the serum phospholipids and milk lipids of the women. As the proportion of C10-Cl4 fatty acids in the milk lipids increased from 10% to 40%, there was preferential retention of three critical n-3 and n-6 fatty acids (ALA, AA, and DHA) at the expense of two relatively abundant nonessential fatty acids, namely stearic acid and oleic acid. In addition, using fatty acid melting point data and the mol fraction of the 9 most abundant fatty acids in the milk, we estimated the mean melting point (MMP) of the milk lipids of the Nepalese women. The MMPs ranged from 29.3 to 40.5 degrees C (median, 35.5 degrees C). These results indicate that: 1) the levels of AA and ALA in the blood of lactating mothers influence the levels of these fatty acids in the milk they produce; 2) when the mammary gland produces a milk that is rich in C10-Cl4 fatty acids, it somehow regulates triglyceride synthesis in such a way as to ensure that the milk will provide the exclusively breast-fed infant with the amounts of the critical n-3 and n-6 fatty acids it requires for normal growth and development; and 3) the melting point of the milk lipid fraction is determined mainly by the mol % of the intermediate chain-length (C10-C14) fatty acids, oleic acid, linoleic acid, and alpha-linolenic acid.