Saliva Experiments

[JudyM]

Does anyone out there have an alternative to saliva that works for the Year 11 Biology prac -
Effect of pH on Enzyme Action. It's from the text Biology in Context- The Spectrum of Life.

If anyone has any ideas I'd love to hear them.

Thanks

[rae]

Hi Judy,
You can buy powdered amylase/diastase from Southern Biological.
You would need to check their website for prices.
We use this for our pracs and it works well as a 1% solution.

Lorrae

[lada]

Yes, we also use amylase for that experiment.
Lada

[JudyM]

Thanks Lada & Rae,

I have tried amylase once before, but I'll give it another go.

Cheers
Judy

[rae]

Judy
If you go ahead and buy the amylase mine came with a package insert with an experiment for using it.
I did some work on this for use with the data logger and came up with something that worked quite well.
Use 1% iodine, 1%Starch and 1% amylase.

Dilute 5ml starch with 5ml distilled H2O, add 1 drop iodine, Add 2ml Amylase solution and mix well. Then time the reaction. The color will change from dark blue to pinky colur to clear when the starch is digested.
I read somewhere that you could then test the solution with benedicts for the presence of glucose.

Hope this of some use to you.
Lorrae

[Wombat]

The effect of pH on enzyme activity experiment using the enzyme pepsin on egg white is a good alternative to a salive expt.

[noona]

We also use egg white & pepsin and it works very well
noona

[ellice]

Hi all,
We are in the middle of Enzyme pracs as well, and trying the egg white and Pepsin for the first time. Do you use raw egg or cooked? The Pepsin is quite old. Could this be affecting results?
Ellice.

[JudyM]

We've never done the egg white & pepsin prac here before.

I'd be grateful if someone could please fax me a copy. Our # is 6772 5697

Thanks so much
Judy

[Labbie]

I also would like a copy of egg & pepsin experiment.

Our fax is 02 9823 7662 attn Sue in Science please

Thank you so much

[ELIZABETH]

Hi Judy and Sue,
We're in the midst of enzyme pracs (again!!!!). Every year look for the best prac I can find to fit the students. This year's version is really good and is all experiemnts are working well.
I've scanned the instructions into this computer and will upload them to this site. The file doesn't look too pretty, but should be openable and usable.
For the pepsin-egg prac, I use an egg white suspension (hard boiled egg white blended fro 5 minutes with 200 mLs water) and it worked a treat.
Good luck
LIZ
P.S. Jude, if you don't have any fresh pepsin, ring me and I'll drop some in.
Liz
P.P.S. Let me know if the file is readable or not - might have to fax it.

[JudyM]

Hi Liz,
I've printed it out for my recipe file & given it to the Bio teacher too.
The prac is for this afternoon & I won't have time to prepare the egg suspension, so we'll just go with the amylase this time. I will definitely be ordering fresh pepsin for next year.

Do you know the difference between clarase & diastase? When I used amylase (clarase) once before that prac didn't work, so perhaps I ordered the wrong thing.

Thanks a lot for your help
Judy
PS. I haven't forgotten about the small motors I still owe you. Promise you'll have them by the end of term.

[rae]

Hi!!

Diastase is just another name for Amylase.

Lorrae

[Whspa]

This is from the Southern Biology catalogue:
Amylase (clarase): may contain reducing sugars.
Amylase (diastase): reducing sugars not detectable in 1% solution.

My biology teacher says you need diastase for artificial saliva pracs.

Hope this helps.
Carol

[JudyM]

I did try the wrong amylase after all.
Thanks everyone for your help.

Cheers
Judy

[RosalieM]

We are doing the pH saliva one today and I am making up the starch solution. Do I need to use the soluble starch or potato starch? Does it matter which?
Rosalie

[JudyM]

Rosalie,

I used soluble starch last week but I don't think it really matters which one you use.
I mix the powder into a slurry with a little cold water then add boiling water, but you could also use a microwave.

Good luck with that prac
Judy