Enzymes

Investigating the effect of pH on amylase activity

Aim

The aim of the experiment is to determine the effects of different pH and the rate of reaction on fungal amylase and starch.

Introduction

The enzyme amylase is found in the human body, it catalyses the hydrolosis of internal glycosidic bonds in polysaccharides, the breakdown of starch into sugars. Amylase is present in human saliva, where it initiates the chemical process of digestion. Enzymes work best at an optimum pH of 7 which is the bodies normal pH. The pH affects the charge of the amino acid at the active site. PH changes affect the structure of an enzyme molecule and therefore affect its ability to bind with its substrate molecules. Changes in pH affect the ionic bonds and hydrogen bonds that hold the enzyme together, which naturally affects the rate of reaction of the enzyme with the substrate. On top if this, the hydrogen ions neutralise the negative charges of the R groups in the active site so that the substrate and the active site do not attract and therefore do not react.

Amylase is an enzyme. Since enzymes are proteins, their secondary and tertiary structures are affected by temperature and pH. The enzymatic activity is closely associated with the structure of the enzyme, so any change in the secondary or tertiary structure leads to a change in enzyme activity. (3)

Amylase is a digestive enzyme found in saliva and in pancreatic secretions to the small intestine. The function of amylase is to catalyze the hydrolysis of carbohydrates, such as the polysaccharide, starch, to the disaccharide maltose. Maltose is subsequently hydrolyzed to glucose by another digestive enzyme, maltase. These glucose molecules are the starting point of glycolysis.
Glycolsis is the first process organisms employ to harvest energy, (ATP), from ingested carbohydrates. In cellular respiration, glycolosis is the initial step in energy production as it converts glucose to two pyruvate molecules. These pyruvate molecules are further processed in the Krebs cycle and then through oxidative phosphorylation to eventually generate a combined ~ 38 ATP’s per glucose molecule processed(1, 2).
Amylase is an enzyme. Since enzymes are proteins, their secondary and tertiary structures are affected by temperature and pH. The enzymatic activity is closely associated with the structure of the enzyme, so any change in the secondary or tertiary structure leads to a change in enzyme activity. (3)

PH changes affect the structure of an enzyme molecule and therefore affect its ability to bind with its substrate molecules. Changes in pH affect the ionic bonds and hydrogen bonds that hold the enzyme together, which naturally affects the rate of reaction of the enzyme with the substrate. On top if this, the hydrogen ions neutralise the negative charges of the R groups in the active site so that the substrate and the active site do not attract and therefore do not react. The optimum pH for most enzymes is pH7.

In the body, amylase works mainly in the small intestines, where the acidity from the stomach has been neutralised by the hydrogencarbonate ions in the pancreatic juices secreted by the pancreas....How does pH affect the activity of the Amylase?

In this investigation I am going to consider how different pH levels will affect the rate in which amylase will break down the starch molecules. I will be measuring the time it takes for a yellow brown liquid to be shown, which would show that there is no starch present in the solution because it would have been broken down by amylase in solutions under ph levelsuv been writing i change it xxits off the internet lol im gonna bring mine in on monday coz word wont let me paste onto here xxsay aswell what starch is/made of and what amylase is aswell xxi didnt use any of the iternet for my bit i got 6 books from libary an just used them xxalso possibly mention how iodine is gonna help get the results (by changing colour)if u dont get a distinction for that what u just sent me ill be well shocked!!do u no how many glucose molecules bond the glgocidic bonds xxif u make ur part b as good as part a ur defoo on to a winner there, what did u get for ur last assignment?yeah i do give me a sec n ill check xxhave u wrote about any of the chemistry side of it in ur part a xxits 1,4 glycosidic bonds and that is how starch is made hence why amaylase works well on it xxthanks hun xxwhat do u mean chemistry? iv only done 200 words for part a, iv struggled really badeverything other than the bonds what u wrote above i didnt understand xxim gonna have to go library in morn n see if they have any books xxremember them circles we were drawing the electronic structureswith the atoms inbio chemistry stuff ha xxChat Conversation End

its 1,4 glycosidic bonds and that is how starch is made hence why amaylase works well on it xx

The function of amylase enzymes are to catalyse and hydrolyse of 1,4 and 1,6 glycosidic linkages of polysaccharides (amylose and amyl pectin) into a variety of products including maltose, dextrin and D-glucose etc. Amylases are obtained from animal, bacterial, fungal and plant sources such as barley, malt and fungi called Aspergillus oryzae. There are a few forms of amylases.

Apparatus

See attached apparatus, and health and safety sheet.

Method

Hypothesis

Null hypothesis - there will be no change in the rate of reaction on enzyme activity.

Alternative hypothesis - there will be a change in the rate of reaction on enzyme activity.

I predict amylase

Results

Group Rate of reaction (seconds) pH pH 2 pH 4 pH 6 pH 10
1 400 80 320 400
2 400 60 330 400
3 400 70 320 400
4 400 100 360 400
Mean 400 77.5 332.5 400
1/t 0.0025 0.0129 0.0030 0.0025

Discussion