Enzymes, Amino acids, Polypeptides!

[oviav]

Right... I have a few question to ask. I sort of missed all if not most of these topics in class due to illness. So I'm just looking for explanations of how you come to answer!

For this question its basd on how lactose-reduced milk is formed in an industrial reactor using the enzyme lactase.
Questions asks: In terms of the way which enzymes work, explain why it is necessary to pass the milk through the reactor several times to reduce the amount of lactose sufficiently.
I have no idea why. Nothing in the Biology Text book !

The others are based upon a Polypeptide chain, in the sequence of:

Lys(cut here by tryp)-Val-Arg(here by tryp)-Ser-Lys(here by tryp)-Ala-Phe(here by chym)-Val-Trp(here by chrym)-Ile-Ile-Glu-Val-Pro-Lys(Tryp here too)

Then it asks: How many amino acid fragments will be produced from this polypeptide if it is incubated with a mixture of trypsin and v8 protease. ok just foudn out chymotrypsin breaks up tyr,try, and phe.

therefore is it 6 0.0??


ii) Explain why trypsin and chymotrypsin break peptide bonds betwen amino acids.

Is this because it Hydrolysises the proteins? I know Trypsin sort of breaks peptide chains at the carboxyl side of the amino acids lysine or arginine!But no idea about chymotrypsin. Never heard of it.


iii) Describe how you would use a biochemical test to shoe a solution contained protein.

I don't know if its Benedic's or Biuret. Biuret maybe? So Sugars with Benedict's solution. Protein with Biuret ??

[oviav]

Anyone out there willing to give me some hints? ;(

Just need to get through these questions, and revise. -.-"

[JackBean]

Give it some time We have to sllep some time also

1) Look at the enzymatic kinetics. The reaction is not linear going to zero.

2) http://www.lmgtfy.com/?q=v8+protease
Let you try to count once again

3) http://www.lmgtfy.com/?q=chymotrypsin
here you have the mechanism:
http://www.mpcfaculty.net/mark_bishop/chymotrypsin.htm

4) http://www.lmgtfy.com/?q=protein+determination
(just two first links give you best answer )

[oviav]

1) Aww man, still not "getting" this. >-<

2) Silly me, mixed up with chymotrypsin and v8 protease! So it's 5?

3) So to do with active sites and substrates :S

4) I guess Biuret is the one!!