Lab22

Lab 22   Phenylalanine Deamination

Purpose: determine that amino acids can be catabolized by enzymatic conversion to molecules that can enter the Krebs cycle.

Procedure: (source: mission college microbiology copyright 2009 by Melanie O’Brien)

1. Working in pairs, label 2 phenylalanine slants
2. Inoculate one tube with Escherichia coli and the other with Proteus vulgaris.
3. Incubate the tubes, with loosened caps, at 35*C until the next lab period.
4. Add 5 drops of ferric chloride to the tube, aiming for the top of the slant and letting the drops run down over the area of bacterial growth.  A positive test will quickly develop a dark green color.

Observations:

Organisms	Result ( + or – )
E. coli	–
P. vulgaris	+

Questions:

Complete the reaction of alanine deamination.

Alanine  + ½ oxygen  reacting with ( Phenylalanine deaminase)  produces – a  by product of  ((  Pyruvic Acid + Ammonia ))  (source: Brandy)