Enzyme Lactase Lab Report

Joshua Valerio
Principles of Biology
Section: Thursday 08:00
29 October 2015

Discussion

The affects of pH, temperature, and salt concentration on the enzyme lactase were all expected to have an effect on enzymatic activity, compared to an untreated 25oC control. The reactions incubated at 37oC were hypothesized to increase the enzymatic activity, because it is normal human body temperature. This hypothesis was supported by the results. The reaction incubated to 60oC was expected to decrease the enzymatic activity, because it is much higher than normal body temperature, however this hypothesis was not supported. When incubated to 0oC, the reaction rate was hypothesized to decrease, and according to the results the hypothesis was supported. Both in low and high pH, the reaction rate was hypothesized to decrease, which was also supported by the results. Lastly, the reaction rate was hypothesized to decrease in a higher salt concentration, which was also supported by the results.
The effects of low pH, in guinea-pigs digestive tract, showed a similar effect to that of human lactase in a low pH environment. The pH levels tested in the guinea-pigs experiment were 2.5, 3.0, 3.5, and the control was 6.5. As the pH became

more acidic, the enzymatic activity decreased. Lower pH levels in the colon of guinea-pigs were associated with higher levels of lactose. The higher levels of lactose indicated a decrease in enzymatic activity, that essentially resulted in diarrhea (Bennet and Eley, 1975). In another study, with lactase from acidophilic fungus, biologist Dr. Isobe, and his partners at Iwate University, characterized a type of β-galactosidase that thrived in acidic pH conditions from 1.5 to 7.0, a much wider spectrum than what the human lactase performed in our experiment. Another condition Dr. Isobe, and his partners, tested were temperature changes. Dr. Isobe directed the experiment into a variety of different temperature environments, before determining 70°C and a pH of 2.5-4.0 was the optimal condition (2013). In the experiment that was conducted in this study, the acidic condition would have been unfavorable, and as temperature increased, the enzymatic activity increased. The human lactase also showed a decrease in enzymatic activity in higher salt concentrations. In a similar experiment, to the one conducted in this study, in small aquatic copepods the effects of temperature, pH, and salt were also observed. As the salt concentration increased, the amount of enzymatic activity decreased. This was determined by removing waste from the digestive tract and separating it’s components to see what amount of lactose, glucose, and galactose was present. According to the figures in the report, the effects of temperature, salt, and pH were similar to what was observed in the experiment conducted in this study(Dutta etal, 2005).
Continuing research of human lactase and enzymatic activity could include a more provincial approach to the conditions.

For example, incubating the samples at different temperatures would create more data points to establish an optimal temperature. From the results in the experiment in this study, it is known as temperature increases, enzymatic activity increase, and vise versa. However, what can not be observed is at what point does the increase in temperature begin to denature the enzyme, above 60°C. Furthermore, assays can be preformed to determine optimal pH, as well. From Dutta’s, and his partners, experiment it shows that there is a range where the Heliodiaptomus viduus’s lactase shows the most activity, which is between 5.0 and 6.0

(2005).

Works Cited

Bennett, A., & Eley, K. (1975). Intestinal pH and propulsion: An explanation of diarrhoea in lactase deficiency and laxation by lactulose. Journal of Pharmacy and Pharmacology, 38(28).

Dutta, T., Jana, M., & Bhattacharya, T. (2005). The Effect of Temperature, pH, and Salt on f β- galactosidase in Heliodiaptomus viduus (Gurney) (Crustacea: Copepoda: Calanoida). Turk J Zool, 2006(30), 187-195.

Isobe, K., Yamashita, M., Chiba, S., & Takahashi, N. (2103). Characterization of new β- galactosidase from acidophilic fungus, Teratosphaeria acidotherma AIU BGA-1. Society for Bioscience and Bioengineering, 116(3), 193-7.