Hi,
What is isoelectric point? And thanks for the advice, I didn't know that there was a point where proteins are least soluble
Are curds good for humans? Or is it bad?
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- Project Question: Finding out which natural acid (fruit juice) would produce the most curds in a certain amount of time, and therefore serves as a better substitute for rennet.
- Project Due Date: 20 June 2009
- Project Status: I am conducting my experiment
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Re: Are curds good for humans? Or is it bad?
Hi Chiazuohui,
Good question. Proteins are composed of amino acids, which can have free carboxyl (COOH) groups or amino (NH2) groups, (all amino acids have at least one amino and one carboxyl group, but these are combined in a covalent peptide bond in proteins). Above a pH of 4.5, and carboxyl groups will have a negative charge (COO-), and below pH 7, the amino groups will have a positive charge (NH3+). The pH at which the negative and positive charges are balanced and give the protein a net neutral charge is called the isoelectric point.
Here is a website that explains the general principle of isoelectric point:
http://en.wikipedia.org/wiki/Isoelectric_point
Here is some additional information about isoelectric point and characteristics of proteins:
http://www.chemistryquestion.com/Englis ... ation.html
Casein has an isoelectric point of 4.6, so is least soluble at this pH. In milk at pH 6.7 the casein would have more carboxyl groups ionized compared to protonated amino groups, so would have an overall net negative charge.
Does this information give you any ideas for your experiment?
Donna Hardy
Good question. Proteins are composed of amino acids, which can have free carboxyl (COOH) groups or amino (NH2) groups, (all amino acids have at least one amino and one carboxyl group, but these are combined in a covalent peptide bond in proteins). Above a pH of 4.5, and carboxyl groups will have a negative charge (COO-), and below pH 7, the amino groups will have a positive charge (NH3+). The pH at which the negative and positive charges are balanced and give the protein a net neutral charge is called the isoelectric point.
Here is a website that explains the general principle of isoelectric point:
http://en.wikipedia.org/wiki/Isoelectric_point
Here is some additional information about isoelectric point and characteristics of proteins:
http://www.chemistryquestion.com/Englis ... ation.html
Casein has an isoelectric point of 4.6, so is least soluble at this pH. In milk at pH 6.7 the casein would have more carboxyl groups ionized compared to protonated amino groups, so would have an overall net negative charge.
Does this information give you any ideas for your experiment?
Donna Hardy