The Nature of Enzymes and the Reactions They Catalyze - Essay Example

Name Course Tutor Institution Enzymes Is a protein compound that speed up or cartelize the reaction rate of a substance. They are made of protein, amino acids and their functions are determined on their shape. They are characterized as a living thing and therefore having life span. Some have long lifespan while others have short life span. Every enzyme has a specific function. The nature of lactoperoxidase Lactoperoxide is a natural enzyme that is characterized in damaging of cell membrane. It is a glycoprotein that has a high haem group of isoelectric point. The enzyme is found in mammals such as pigs, humans and cows which are associated with milk production, tears and saliva. Lactoperoxide kills bacteria and causes inhibition in the presence of thiocyanate, pseudo halogen and hydrogen peroxide. It is naturally found in antimicrobial peptide which is used in food processing industries. Different studies of raw milk preservation through activating natural lactoperoxide system were advanced. Lactoperoxide (LP) is a non-immunoglobulin glycoprotein enzyme with haeme structure that contains one molecular iron per mole. It has 1% content of protein. LP is described by its stability of heat, since it retains normal in milk pasteurization, this is to say; temperature is retained at 72ºc every 15 seconds or 63ºc for every 30 minutes and destruction done at 80ºc. Cow’s milk is actively associated with LP, though it varies in its content range from 13 mg/L to 30 mg/L. However, there are various factors that affects the concentration of LP, these factors include; the age of the cow, breed, cows nutrition, its location state and the health status of the cow as well as daily variations. Lactoperoxidase enzyme does not have activity of antibacterial. Natural component of antibacterial system is formed through combining hydrogen peroxide and thiocyanate that gives rise to lactoperoxidase. It has been proven that LP (lactoperoxidase) has both bactericidal and bacteriostatic micro-organisms since it is activated by hydrogen peroxide and thiocyanate reaction, and LP acting as catalysis (Arthur P & Riley Pp 9). LPs effectiveness in maintaining quality hygienic raw milk storage at a limited time has been established. Its effectiveness depends on the initial amount that microbiological contaminants contain. The temperature of milk during storage is also considered. Preliminary bacteriotic effects are exerted to milk by lactoperoxidase system. Its activation delays psychotropic bacteria growth in milk thus the spoilage of milk is also delayed compared to refrigeration. The purpose of LP system is to preserve milk in its original content. However, LP is not primarily responsible for providing safer milk for human consumption. Long lasting bacterial effects of milk from cows is activated by LPs due to higher level of antimicrobial components. In mastitic milk LPs is not that effective unlike in milk that comes out from healthy cows since they have higher reductive agent concentration. catalase enzyme is highly active in mastitic. Lactococci and non-pathogenic streptococci effects of lactoprotoxidase are less. The sensitivity of strains varies in different ways by different inhibitors and cell structures. Catalytic enzyme has a defiance of Bacteria lactic acid. On production of yoghurt, LP was sensitive to starter culture when the hydrogen peroxide concentration is higher. The lesser the amount of hydrogen peroxide used its effects yields a positive result as the yoghurt produced has a smooth texture. Lactoperoxidase system was not completely able to destroy monocytogenes growth but it has the ability to delay its growth in milk. However, lactoperoxidase occurs in exocrine milk secretion gland. It is a prominent enzyme and a protective agent of non-immunoglobulin protein which prevents mammary gland from microbial invasion. Oxidative mechanisms are used by peroxidase enzyme to kill bacteria. (Bøgh-Sørensen,pg 57). Another effect is that, Protein in camel milk were undenatured after subjected to heat for 30 min between 80°c and 90°c. Protein in camel milk showed stability of heat as compared to cow’s milk. Milk denaturition degree varies in percentage 32-35% and 73-81% in camel and cow respectively. Generally, there was more resistance of lactoperoxidase in camel proteins as compared to cows’ protein milk. Methods of assessing Lactoperoxidase enzyme in milk Samples of twenty raw freshly morning cow’s milk were randomly obtained from different farms and collecting centers. Collected samples were labeled in polyethylene sacs that were sterilized. The polyethylene sacs were transported for laboratory tastes immediately while kept in an ice box that was well insulated at 5°c. Two equal parts of the samples were divided for each sample in the laboratory i.e. 1litre. One portion was sterilized (500gm) by lactoperoxidase activation, later subdivided in two equal parts (250 gm) and stored at 5°c (refrigeration) or 30 °c (ambient temperature). The remaining major portion (500gm) was also subdivided to two and kept as control. In lactoperoxidase system (LP-s) activation first, potassium thiocyanate of 0.017 gm was added to every litter of milk, there by 15 ppm of thiocyanate content was increased. Second, sodium percarbonate of 0.034 gm was added to every litter of milk and thoroughly stirred up. Percarbonate decomposed after coming into contact with water into hydrogen peroxide and carbonate in correspondence with hydrogen peroxide of about 10 ppm and practice code 1988 as IDF recommended. Third, each sample was subjected to heat treatment detection of Guaiac test so as to prove if the milk was raw. Hygienic quality determination tests were carried out in different stages like a) titratable acidity determination according to Janet b)the technique test of methylene blue reduction (MBR) as by Young W. Park c) the test of clot-on-boiling (COB) according to Arthur P. Riley. (Young W. Park,pg 330) Lactoperoxidase significance in milk The presence of antimicrobial natural system in milk, lactoperoxidase system, is used in areas that lack the refrigeration mechanism in the preservation of raw milk. Lactoperoxidase system preservation of raw milk is mostly recommended in dairy processing industry during storage and exploration. Lactoperoxidase has 612 residues of amino acids with an approximate of 78kDa molecular weight. 10% of its total weight of carbohydrate moiety is in Lactoperoxidse. Human milk has a small amount of lactoperoxidase contents compared to bovine milk. Mature milk has less content of LP unlike colostrums that has more content of lactoperoxidase. Until the babies are unable to secrete peroxide in saliva, its level remains high. At 78 °c per 15 seconds, there is a complete inactivation of lactoperoxidase. To improve the thermo stability of LP there was need of higher strength. (Ling,106) Plasmin enzyme nature Plasmin component is a complex system that has various active enzymes present in milk. Milk indigenous enzymes are associated with casein micelles, globule membrane of milk fats, somatic cells and serum are said to be blood origin. The enzymes may be used in animal health encouragement or milk thermal history. The enzymes can result to desirable milk changes or quality deterioration in milk and also protective effects are also offered. Plasmin is an indigenous predominant milk enzyme proteinase. It is part of protease complex milk system consisting of plasminogen, inactive precursor and plasminogen activators where plasmin is catalyzed from plasminogen. Plasminogen and plasmin are associated with milk casein micelle and they are from mammal’s blood. Plasmin enzyme has an optimal of 37ºc at 7.5 pH and it is serine protease. Plasmin is effective in dairy production manufacturers. Serum milk has most of the plasmin inhibitors. Raw milk heated at 120ºc/15min or 142ºc / 18sec was necessary during storage for inhibiting plasmin . A-casein is less susceptible; ß-casein is more sustainable while k-casein is resistant to plasmin breakdown. In contrast, ß-lactoglobulin and a-lactalbumin milk proteins are resistant to plasmin action to some extent. Plasmin reaction Plasmin enzyme has its reactions in milk as a catalyst. plasmin, plasminogen activators and plasminogen sensitive tests were carried out and it was relevant to bovine. After the reaction of plasmin substance of hydrolysis, dissolving agent was added. The last step, there was a use of samples with large amount of substrate concentration compared to the rest of methods and the preparation of the previous samples were avoided. Detection level, sensitivity, and repeatability tests for plasminogen and plasmin methods of previous enzymes were improved with a substrate of synthetic. There was assay measuring conversion of plasminogen to plasmin. Centrifuge of bovine milk for separation of cream, somatic cell and skim test were carried out. Casein and serum were separated from skim milk centrifuge. Reaction between reducing sugar and proteins resulted to non-enzymatic browning. Effects of plasmin Sub-clinical mastitis effects on cow milk of plasmin and plasminogen of high yields was investigated. The measurement of plasmin and plasminogen activation from mastitic sample quarters was used. There was an increase of 21% of plasminogen and 82 % of plasmin while that of glucosaminidase was 37%. The only normal component that was distributed was plasminogen while the rest of the components showed less or more distribution skewed. Other components were related with plasminogen and plasmin. However, as other components increased, the higher the plasminogen plateaued. Plasminogen did not increase further with other component after application of hash inflammation. Similar tendency was seen in plasmin though at a lower rate. The increase of non linear was triggered by samples of mastitic treatment with acid catalysts. Its activity was when it interacted with protein acid-labile inhibitors. Dissociation of plasmin and plasminogen from casein micelles was led by mastitic. Epithelial integrity indicator came as a result of close relation between plasmin and glucosamidase. The leakage of glucosamidase into milk is contributed by plasmin as epithelial protein membrane lining is degraded. The lactation stage did not affect antitrypsin and plasminogen plasma protein and as a result, there was no indication of them being transported from plasma to milk. Plasmin assessing method There are two ways in which milk is processed while assessing plasmin; these ways include subjection to high and subjection to minimal temperature. Some manufacturers use treatment method of preheating before applying ultra high temperatures (UHT) in prolonging plasmin shelf life. There were random preheat treatment considering time holding and temperature. Application of preferred preheat treatment range to milk, as batches of powder milk that was skimmed and heated at low temperature. Preheat treatment that was > 90ºc while equal or less to 80ºc; the proteolysis plasma type was thereby increased. During different flow rate and temperature of milk treatment condition, denaturation of lactoperoxidase, beta-lactoglobulin and alkaline phosphates changed in proteolytic activity. In the process of continuous pasteurization flow, the components of milk are changed by inducement of high heat. Susceptible of less time holding of their differences was observed. Denaturizing effects information are different at all stages. The assessing method was also carried out in human beings. Two mothers of un-sacked breast, were scanned for milk duct of BB (n=21) and another group was obtained purposely for breast feeding. The duct was monitored for two different days for 5minutes each without inducing ejection factor on the milk. Testing weighing was used to measure breastfeed milk sample. Plasmin significance Plasmin splits proteins as a proteolytic enzyme. It is responsible for pasteurized milk bitterness since it is stable with high heat. Plasmin plays a role in adding of flavors development and ripening of cheese, as it is in this case, the cheese is specified as Swiss cheese. Indigenous proteinase is principled to plasmin though cathepsin D presence is at a very low level. Plasmin consists of various types of active enzyme in milk and the enzymes include activators, plasminogen and inhibitors. The component works as fibrin clot solubilizer. Plasmin components enter in milk via mammocyte defective membrane which is elevated at mastitis infection and at the late stage of lactation. It is associated with a component in milk known as casein micelles as it is converted to cheese curd. (Panesar Parmjit .S, pg 65) In raw milk storage, proteolysis protein production to protease and native proteases is attributed with a of combination psychotropic bacteria. Detrimental changes or benefits are made by these proteases on milk products that are specific. Plasmin being a major milk native protease is important in the ripening of cheese. A condition of cheese making and milk storage affects plasmin level in casein and milk fractions. Microbial protease that originates from psychotropic microorganism, in casein curd the level of plasmin is increased indirectly. To benefit the dairy products quality, the microbial proteases and plasmin system relationship in milk control level means are provided. The enzymes role in UHT treatment as a heat resistant has not been fully understood. Conclusion The presence of lactoperoxidase and plasmin in milk are of importance in the preservation process. The presence of various enzymes degrades proteins in milk. The complete breakdown of the proteins affects cheese ripening, clotting of milk and the dairy flavor texture. The presence of these enzymes in milk has both positive and negative effects. Lactoperoxidase forms a natural enzyme in combination with thyacene and hydrogen peroxide. They function well after being subjected to hymogenation that affects protein, fat globules and microbes. As lactoperoxidase is activated plasmin is naturally found in milk. Milk has a content of large indigenous enzymes that are active. Heat subjection is applied to plasmin system so that it may function since the enzymes are not affected by heat. The functioning of the enzyme is activated by proteases activator. The system is more effective in places where refrigeration system can not be applied due to either unavoidable circumstance for instance lack of electrification system. The enzymes work in destroying bacteria’s which are present in milk. Thereby, allowing the stored milk to last for a long period of time. They work well under a certain optimum pH level and preferred temperature. References Arthur P. Riley, New issues in food policy, control and research, nova publishers, New York, 2007. Bøgh-Sørensen, Leif. Food preservation techniques. New York: Woodhead Publishing, 2003. Janet R. Ling, Dietary Protein Research Trends , Nova Publishers, New York 2007 Young W. Park, George F. W. Haenlein. Handbook of milk of non-bovine mammals. Landon: Wiley-Blackwell, 2006. .S, Panesar Parmjit. Enzymes In Food Processing: Fundamentals And Potential Applications. London: I. K. International Pvt Ltd, 2008. Read More