Milk alkaline proteinase

Grufferty, M B; Fox, Patrick F.

doi:10.1017/s0022029900033409

Cited by 223 publications

(159 citation statements)

References 72 publications

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“…Specifically, several studies have reported significant protection of plasmin in the presence of sodium caseinate, and enhanced inactivation in the presence of β-lactoglobulin [1,22,29]. Heat inactivation of plasmin in the presence of β-lactoglobulin is thought to be linked to the formation of thiol-disulphide bonds with unfolded β-lactoglobulin [13,16]. Pressurisation also induces unfolding of β-lactoglobulin [9,18], and consequently exposes the highly reactive internal thiol group, which may be able to undergo thiol-disulphide interactions with disulphide groups linking structural subunits in the plasmin molecule.…”

Section: Discussionmentioning

confidence: 99%

“…It has been reported that, at pH values near neutral, β-lactoglobulin unfolds readily and irreversibly to expose its reactive sulphydryl group, which can then undergo sulphydryldisulphide interchange reactions, while at spheric pressure [5,13,32]. However, very little is known about this reaction at elevated pressures and thus, in this study, the effect of high pressure on this digestion reaction was examined.…”

Section: Minsmentioning

confidence: 98%

“…3.4.21.7) [5]. Most of the potential plasmin activity in milk is in the form of the inactive precursor plasminogen, which is converted to active plasmin by a heterogeneous group of plasminogen activators [2,13].…”

Section: Introductionmentioning

confidence: 99%

“…Plasmin activity influences the quality of many dairy products [5,13]. Plasmin is an alkaline serine proteinase with a pH optimum of 7.5, which readily hydrolyses β-casein and α s2 -casein and, more slowly, α s1 -casein [8].…”

Section: Introductionmentioning

confidence: 99%

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Barostability of milk plasmin activity

Scollard

Beresford

Murphy

et al. 2000

Lait

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-The influence of high pressure (HP) on the stability and activity of the milk alkaline proteinase plasmin was examined. Assays of enzyme activity following HP treatment of plasmin in phosphate buffer (pH 6.7) indicated that the enzyme was extremely pressure stable, retaining almost all activity even after treatment at 600 MPa for 20 min at 20 °C. Plasmin was also extremely stable when HP treated in buffer containing 25 mg . mL -1 sodium caseinate, and in cheese. However, HP treatment in buffer containing 5 mg . mL -1 β-lactoglobulin resulted in enzyme inactivation at pressures > 400 MPa, indicating that the presence of β-lactoglobulin greatly destabilises the enzyme under high pressure, which is analogous to the effect of this protein on the heat stability of plasmin. In separate experiments, hydrolysis of β-casein by plasmin at 20 °C for 30 min at various pressures (300-800 MPa) was studied. Parallel control incubations were performed at atmospheric pressure. Urea-PAGE analysis of digests showed that primary proteolysis of β-casein was decreased at P > 400 MPa. As judged from RP-HPLC analysis, production of 2%-TCA soluble peptides by plasmin appeared unaffected at P < 700 MPa, above which pressure the rates of peptide production decreased. Overall, plasmin is relatively pressure stable in most systems and can hydrolyse its preferred substrate (β-casein) at pressures up to 700 MPa, but is sensitive to destabilisation by denatured β-lactoglobulin. plasmin / high pressure / specificity / stability Résumé -Stabilité de la plasmine sous l'influence de hautes pressions. L'influence des hautes pressions sur la stabilité et l'activité de la plasmine bovine a été examinée. Les déterminations de l'activité enzymatique suivant le traitement à hautes pressions de la plasmine dans une solution tampon phosphate (pH 6,7) a indiqué que l'enzyme était très résistante à la pression, conservant presque toute son activité, même après un traitement a 600 MPa pendant 20 min à 20 °C. Lorsque la plasmine a été traitée dans une solution tampon contenant 25 mg . mL -1 de caséinate de sodium ou dans le fromage, elle s'est aussi avérée très stable. Cependant, le traitement à hautes pressions dans une Lait 80 (2000) 609-619 609

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Section: Discussionmentioning

confidence: 99%

Section: Minsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Barostability of milk plasmin activity

Scollard

Beresford

Murphy

et al. 2000

Lait

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“…Plasmin regulates its own activity as long as it is involved with urokinase in plasminogen activation into plasmin [26]. Autoregulation of PMN proteases corresponds to the interaction between the different classes of proteases.…”

Section: Autoregulationmentioning

confidence: 99%

Polymorphonuclear proteolytic activity and milk composition change

Roux¹,

Laurent²,

Moussaoui³

2003

Vet. Res.

118

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-Relationships between Quarter Milk Cell Count (QMCC) and Tank Milk Cell Count (TMCC) with milk biochemical and technological parameters in milk and dairy products were investigated. All parameters measured were affected by the increase of TMCC and QMCC between 0 and 600 000 cells/mL. The variable effect of lactation stage which is different for different authors, is discussed. The three mechanisms, measured during the inflammation of the udder, implicated in the modification of milk quality are described (a decrease in synthesis, a decrease in the milk barrier permeability and an increase in proteolytic activities). The direct effect of plasmin in caseinolysis is well known; the specific role of the increase of somatic cells (especially PMN) in the modification of milk quality is described. Several specific proteolytic activities of PMN are described and the impact of these activities on caseinolysis is evaluated. Two hypothetical mechanisms of caseinolysis by PMN are suggested and a synthetic scheme of the role of plasmin, bacteria and somatic cells in caseinolysis is discussed. caseinolysis / mastitis / milk / PMN proteases / SCC

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Milk Minor Constituents, Enzymes, Hormones, Growth Factors, and Organic Acids

Rodrigues

2013

Milk and Dairy Products in Human Nutrition

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Milk and derived products contain essential nutrients, such as proteins, lactose, minerals, vitamins, and enzymes. Additionally, despite of their low concentrations in milk, many other minor constituents present important physiological and/or technological roles (e.g. hormones, growth factors). Dairy industries face many challenges regarding milk processing. Also, the full knowledge on these constituents' physiological roles and effects on health is still lacking. Technological advances, innovative research approaches using metabolic engineering, systems and synthetic biology, and novel production methods will allow the production of higher amounts of such constituents, to produce them in such a way that recovery is easier and to produce differentiated compounds, thus revolutionizing the fields of personalized nutrition and functional foods. This chapter focuses on the description of the minor milk constituents, their applications and main technological challenges. Future perspectives and concerns related to these constituents are discussed.

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Milk alkaline proteinase

Cited by 223 publications

References 72 publications

Barostability of milk plasmin activity

Barostability of milk plasmin activity

Polymorphonuclear proteolytic activity and milk composition change

Milk Minor Constituents, Enzymes, Hormones, Growth Factors, and Organic Acids

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