optimum pH for salivary amylase...confused!

[eviemcn89]

i dont understand in the iodine test thing. when ur result comes out and you have mixed ur starch with ur amylase and added the iodine in it and it changes colour n it cud b black blue or orange. but what does that tell you about which is the optimum pH? is it that the more starch then the better pH? i duno...HELP!! im so confused...by the way i hava report due tomorrow on this.Thank you!!

[mith]

the enzyme converts starch to sugar, the iodine turns color(blue/black) if there is starch.

What does it mean if the solution does not turn colors?

[cracked_doc]

I think it means that the pH was not optimum and though the enzyme was present the starch was not converted to glucose due to lack of optimum pH.correct?
does anyone know the pH of starch?
If we add water in the mixture of starch, amylase and iodine the pH would become 7 whereas the optimum pH for amylase is 6...so?

[jrzgrlkpr]

you guys have got most of the major elements of this expirement...

i assume you have added starch and amylase together at different pH's and allowed the to incubate and are now using iodine to preform the Lugol's test. The iodine detects the amount of starch in your solution. As you know, amylase helps to break down starch into maltose. Thus, the relationship between the amount of enzyme activity and the amount of starch will be inverses. The more enzyme activity, the less starch and the more starch, the less enzyme activity. If the solution is amber (the same as the iodine) then there is no starch present. This would mean that the amylase has broken down all the starch (the enzyme performed very well at this pH) if the solution turns blue then there is moderate amount of starch present, and if it turns black then there is a large amount of starch present. Thus the darker the solution (the more starch there is) and the least enzyme activity. Therefore the pH where your solution is amber after you put in iodine, is your best bet for optimum pH b/c that is the pH at which the most starch was broken down.