Comparison of the Abilities of Trichloroacetic, Picric, Sulfosalicylic, and Tungstic Acids to Precipitate Protein Hydrolysates and Proteins

Greenberg, Norman A.; Shipe, W.F.

doi:10.1111/j.1365-2621.1979.tb08487.x

Cited by 62 publications

(45 citation statements)

References 12 publications

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“…Virtually no reaction was observed, indicating that the supernatant contained oligopeptides with <7-l 5 amino acids (the minimum size required for dye binding, Mayer et al 1986). This result is consistent with those of Greenberg and Shipe (1979), who found that TCA precipitation left dissolved peptides of generally ~4 amino acid residues. Nevertheless, we caution that TCA precipitation is variable in its molecular weight cutoff, depending on factors such as types and concentrations of peptides and other materials in solution.…”

Section: Methodssupporting

confidence: 92%

Bioavailable amino acids in sediments: A biomimetic, kinetics based approach

Mayer

Linda

Sawyer

et al. 1995

Limnology & Oceanography

180

141

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We developed a biomimetic approach, based on direct incubation with proteolytic enzymes, to measure bioavailable amino acids in sediments. The kinetics of release of monomers and oligopeptides, which are amenable to absorption by cells, is measured as either individual or total amino acids. Microbial proteases incubated with fresh sediments yield amino acids at a similar rate as gut juices from a deposit-feeding holothuroid.Amino acid release from fresh sediment was dominated by a slow hydrolysis step from a refractory substrate, which can be described with a first-order rate law. Typical rate constants for release were in the range 0.15-0.52 h-l, consistent with gut residence times of deposit feeders.

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Section: Methodssupporting

confidence: 92%

Bioavailable amino acids in sediments: A biomimetic, kinetics based approach

Mayer

Linda

Sawyer

et al. 1995

Limnology & Oceanography

180

141

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“…The large peptides of the ␤-casein hydrolysate were precipitated by 5-sulfosalicylic acid (3% final concentration) (12). After centrifugation to remove the 5-sulfosalicylic acid-insoluble peptides, the supernatant was diluted with an equal volume of 100 mM lithium chloride-68.5 mM sodium citrate (pH 2.2) and filtered through a 0.45-m-pore-size filter (Millipore).…”

Section: Methodsmentioning

confidence: 99%

The extracellular PI-type proteinase of Lactococcus lactis hydrolyzes beta-casein into more than one hundred different oligopeptides

et al. 1995

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The peptides released from ␤-casein by the action of P I -type proteinase (PrtP) from Lactococcus lactis subsp. cremoris Wg2 have been identified by on-line coupling of liquid chromatography to mass spectrometry. After 24 h of incubation of ␤-casein with purified PrtP, a stable mixture of peptides was obtained. The trifluoroacetic acid-soluble peptides of this ␤-casein hydrolysate were fractionated by high-performance liquid chromatography and introduced into the liquid chromatography-ion spray mass spectrometry interface. Multiply charged ions were generated from trifluoroacetic acid-soluble peptides under low nozzle voltage conditions, yielding the MH ؉ mass of each eluted peptide. All peptides corresponding to each of the MH ؉ calculated masses were determined. In those cases in which different peptides were possible, further identification was achieved by collision-induced dissociation under higher nozzle voltage conditions. Hydrolysis of ␤-casein by PrtP was observed to proceed much further than reported previously. More than 40% of the peptide bonds are cleaved by PrtP, resulting in the formation of more than 100 different oligopeptides. With the exception of Phe, significant release of amino acids or di-and tripeptides could not be observed. Interestingly, one-fifth of the identified oligopeptides are small enough to be taken up by the oligopeptide transport system. Uptake of these peptides could supply L. lactis with all amino acids, including the essential ones, indicating that growth of L. lactis might be possible on peptides released from ␤-casein by proteinase only.Lactococci have very limited capacities of synthesizing amino acids and therefore must utilize exogenous nitrogen sources for optimal growth. The amino acid requirement is strain dependent, but Glu or Gln, Ile, Leu, His, Met, and Val are essential for the growth of most Lactococcus lactis strains (6). The addition of several other amino acids was found to be growth stimulatory (34,25). The concentrations of essential amino acids in milk are very low, especially those of Ile and Leu (less than 1 mg/liter) (27). Moreover, the concentrations of other free amino acids are too low to explain the growth of L. lactis to the cell densities normally reached in coagulated milk (27,44). Thus, for optimal growth in milk, lactococci depend on the utilization of milk proteins, such as caseins. Casein hydrolysis by lactococci is mediated by a complex proteolytic system which includes a cell envelope-located proteinase (P I -or P III -type proteinase [PrtP]) and several peptidases (for recent reviews, see references 31, 32, and 42).According to proposed models, PrtP is involved in the first step of casein degradation (32, 39). The action of purified PrtP on ␤-casein has been studied extensively (28,29,33,46,47). After separation of the proteolytic products by reverse-phase high-performance liquid chromatography (HPLC), the different peptides are collected, purified when needed, and identified by biochemical methods (i.e., amino acid composition, determina...

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“…With respect to dietarv Drotern. this system is designed to fractionare into ruminaliy degrad_ able and undegradabie protein and into unavailabie p.ot"in (Chalupa 1992 Roe et al (1990). Non-protein nitrogen content was estimated using sodium tungstate as a precipitating agent according to the procedure of Greenberg and Shipe (1979 HFCM hadhigher (P < 0.05) calcium (Ca) and lower (P < 0.05) phosphorus (P) and magnesium (Mg) levels relative to LFCM and higher (P < 0.05) Ca and lower (P < 0.05) P contents relative to regular canola meal (Table 3). No differences were observed in mineral composition between regular canola meal and LFCM except for P which was higher (P < 0.05) in LFCM relative to regular canola meal.…”

mentioning

confidence: 99%

Chemical characterization and nutrient availability of high and low fiber canola meal

Mustafa¹,

Christensen²,

McKinnon³

1996

Can. J. Anim. Sci.

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. 1996. chemical characterization and nutrient availability of high and low fiber canola meal. Can. J. Anim. Sci. 76: 579_586. Taii-end dehulling separates regular-canola meal (CM) into low (LFCM) and high (HFCM) rrU". nactlons. The study was designed to study i!-: .ff.^.F of tail-end dehulling of cM on the chemical composition, ruminal nutlenidegradability, ani intestinal"protein avaiiability ofthe resulting HFCM and LFCM fractions' Relative to LFCM and CM, HFCM had"higher g.i o.os; neutrat (Nor; and acid lAor; a.t.tg.nt fiberand acid detergent lignin (ADL) leveis. Canola meal had i1fi lfl o.b5) ADF and ADL but not NDF relative to LF-CM. Crude protein (CP) was lower (P < 0'05) in HFCM than in cM uria *us, lower (r < 0.05) in cM than in LFCM. Neutral and acid detergent insoluble cP followed the pattem of NDF and ADF, respectively. piotein fractionation showed no difference in non-protein nitrogen between the three meals'True protein was lower (p < 0.05) in HFCM than cM and LFCM. Sub

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Comparison of the Abilities of Trichloroacetic, Picric, Sulfosalicylic, and Tungstic Acids to Precipitate Protein Hydrolysates and Proteins

Cited by 62 publications

References 12 publications

Bioavailable amino acids in sediments: A biomimetic, kinetics based approach

Bioavailable amino acids in sediments: A biomimetic, kinetics based approach

The extracellular PI-type proteinase of Lactococcus lactis hydrolyzes beta-casein into more than one hundred different oligopeptides

Chemical characterization and nutrient availability of high and low fiber canola meal

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