Some amino acids confer properties to the protein which can be used in the laboratory: Met binds certain heavy metals which are used in X-ray structure determination and reacts with cyanogene bromide (Br—C=N) to cleave the protein at specific sites. Cys and Lys are easily labeled with reactive probes. Aromatic amino acids, in particular Trp absorb UV-light at 280 nm, this can be used to measure protein concentration. In addition they show fluorescence, which can be used to measure conformational changes in proteins.


1.1. Which of the following statements is/are true about amino acids?

1) All protein forming amino acids are chiral.

2) Threonine has two chiral centres.

3) Only L-amino acids occur in living organisms.

4) All amino acids have a pI-value.

1.2. Define the isoelectric point of a compound.

1.3. Glycine is chiral because the a-carbon contains only 3 different substituents.

1.4. Connect the following amino acids with their 1-letter code:

2) Tryptophane B) V

3) Aspartic acid C) W

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