The Effect on the Activity of Enzyme Lactase - Lab Report Example

Effect of Temperature on Lactase Enzyme This study investigated the effect of temperature on the activityof enzyme lactase. Using mil as the substrate and drops of enzyme at temperatures 00C, 200C, 370C and 600C, this study examined the rate of lactose hydrolysis by measuring the amount of glucose produced at each temperature using reagents strips. The results show that lactase activity is low when temperature is low at 00C but improves with increasing temperature up to 370C after which activity drops sharply. Low activity at low temperature is due to low activation energy exhibited by lactase enzyme while low activity at higher temperature is because lactase enzyme was denatured. Introduction Enzymes can be defined as biological molecules that catalyze metabolic reactions that sustain life. Enzymes are made of a complex protein and catalyze specific chemical changes within the body of animals and plants such as digestion of food to produce nutrients for the living organism thus the activity of all enzymes are controlled by the enzymes. Enzymes exhibit three major characteristics: increase rate of reaction, act specifically only in one substrate to produce products and can be regulated from a level of high activity to low activity and vice versa. This can be achieved by regulating certain factors affecting enzyme activity such as substrate concentration, pH, enzyme concentration and temperature (Bettelheim, et al, 2007). Lactase is a digestive enzyme that catalyzes the breakdown of lactose, a disaccharide sugar into simple sugars that can easily be digested. Lactose structure is made up of two rings which require a lot of energy to be broken down into two molecules of simple sugars. Lactose enzyme catalyzes this reaction by reducing the amount of energy required for the hydrolysis of lactose into two molecules of monosaccharide (Jones et al 2013). Lactase is an essential enzyme for mammals necessary to breakdown lactose into simple sugars that can easily be absorbed, thus in lactating animals, this enzyme is available. However, as human beings grow older, they lose their ability to produce lactase enzyme, a condition often referred to as lactose intolerant. Many biotechnology companies have come up with high quantities of lactase enzyme which is used by lactose intolerant individuals. In this regard, lactase enzyme is added into milk thus lactose is predigested before ingestion. In the definition of enzyme above, we mentioned that enzymes are proteins hence just like other proteins; temperatures are likely to affect them. According to (), high temperatures denatures enzymes’ structures hence their specificity is destroyed and they cannot fit with their substrate in order function well thus reduce the rate of hydrolysis of lactose into glucose and galactose (Toole & Toole, 2004). It is therefore important to determine the specific optimal temperatures for enzymes since most enzymes are used in biochemical reactions in commercial processing and manufacturing. This laboratory report investigated the effect of temperature on the activity of lactase enzyme. The objective of the study The objective of this study is to demonstrate the action of an intestinal enzyme, lactase by monitoring the breakdown of lactose into galactose and glucose and investigate how its activity is affected by temperature. Methodology Materials 4 cups of milk Container of apple juice Drops of lactase enzyme Reagent strips Two 25 ml graduated cylinders Hot pot used as heating device Test tube racks and thermometer Procedure 10 ml of milk sample was measured and transferred into each of the four test tubes. The glucose concentration in each standard solution bottles was then measured using reagent strips. This was recorded as “beginning glucose concentration”. The first, second and third test tubes were then placed in ice, room temperature and warm water bath at 370C respectively. The fourth test tube of milk was then heated to boil so that the temperature is between 800C and 1000C before adding two drops of lactase enzyme into each test tube. The contents in the test tube were then left to react for three minutes before taking the new glucose concentration for the solutions using fresh reagent strip. This procedure was repeated for blanks (controls) for each of the four test tubes samples above. The concentrations for each of the four test tubes were then recorded against their respective temperatures in a data sheet. Results Table 1: Glucose Concentration against Different Temperatures Temperature 00C 200C 370C 1000C Glucose measured (mg/dl) Control 0 0 0 0 Glucose measured (mg/dl) Addition of lactase 50 1000 2000 0 The above table shows the results of glucose concentrations recorded at different temperatures for the control test tubes as well as tubes that had addition of lactase enzyme. Figure 1: Effect of Temperature on Lactase Enzyme Activity Discussion This study had hypothesized that temperature affects the rate of lactase enzyme activity. After analyzing the data from the hydrolysis of disaccharide (lactose) to monosaccharide (glucose and galactose) using lactase enzyme at different temperatures, this hypothesis was proven correct. Lactase enzyme played a very important role in enhancing the rate of hydrolysis of lactose to glucose and galactose when the temperature was increased from zero to 200C and to 370C. It is however important to note that higher temperatures above 370C reduces lactase activity and at 600C the enzyme activity is zero. As we hypothesized earlier in this lab experiment, higher temperatures denatured lactase enzyme and that’s why there was no glucose measured in test tubes with samples boiled at 600C. Low temperature levels show low rate of lactase enzyme activity while increasing temperatures results into increase activity. At relatively low temperatures lactase enzyme activity is severely slowed down as shown in the figure 1 and table 1. It is however important to note that there is still some activity because low temperature do not denature enzymes. This was so because at low temperatures, lactase enzyme hydrolysis exhibit low activation energy. According to Lean (2006), the optimal temperature for plant enzymes is 250C while that of animals is approximately 370C to 400C. This can be seen clearly in the table 1 where 370C gives the highest rate of conversion of lactose to glucose. These results show that enzymes are very sensitive to effects of temperatures and the surrounding environment. There was no hydrolysis at temperatures above 600C because they were destroyed. In the introduction, we had stated that the third characteristic of enzymes is that they are specific thus this specificity explains high rate of activity at 370C. Since the body temperature of most human beings is at this temperature, this explains why lactase is an animal enzyme. Moreover, since lactases are proteins they are denatured at higher temperatures hence their structured are destroyed and cannot link well with their specific substrates. References Bettelheim, F, March, J, & Brown, W. (2007). Introduction to Organic and Biochemistry. Belmont, CA: Brooks/Cole Jones M, Fosbery R, Gregory J, & Taylor D. (2013). Cambridge International AS and A Level: Biology Course Book (Third Edition). Cambridge: Cambridge University Press Lean, M.E.J. (2006). Fox and Cameron’s Food Science, Nutrition & Health: 7th Edition. Boca Raton: Taylor & Francis Group. Toole, G & Toole S. (2004). Essential as Biology for OCR, Cheltenham: Nelson Thornes Limited. Read More