22 CHEMICAL COMPONENTS OF CELLS (2) 



Exercise IV 



a 

 o 



Unknown 

 amino acid 



Protein 

 hydrolysate 



Unhydrolyzed 

 protein 



Label each sample directly on the paper below 

 the line, as shown on the diagram. 



The samples are applied to the paper with a 

 fine glass capillary. Draw a little solution into 

 a capillary, and touch it to the paper at a pencil 

 dot. Let this dry, and repeat. Each spot should 

 be not more than 3 mm in diameter. Two such 

 superimposed applications should be enough 

 with the amino acid solutions, and four with 

 the protein and protein hydrolysate solutions. 

 It will be advantageous to place your unknown 

 amino acid in the middle, between the third 

 and fourth known amino acids. Now roll the 

 sheet into a cylinder, and tie the edges together 

 with needle and thread, leaving a gap, as shown 

 in the diagram and as demonstrated by your 

 instructor. 



Pour 30 ml of solvent (formic acid : isopropa- 

 nol:water = 10:70:20) into a quart jar. Line 

 the walls of the jar with a piece of filter paper 



dipping into the solvent in order to help saturate 

 the atmosphere. Splash the solvent about. Now 

 stand your filter paper cylinder in the jar, keep- 

 ing it away from the walls, close the jar, and let 

 it stand quietly. Wait until the solvent has risen 

 within 0.5 cm from the top of the paper before 

 removing the cylinder and letting it dry. Cut 

 the threads, dip the paper into the ninhydrin- 

 acetone reagent, and set it aside to dry. After 

 the acetone has evaporated, place the paper in 

 the warm oven (80°) for a few minutes. Do not 

 overheat! Remove the paper (you may now 

 handle it), and immediately outline with pencil 

 the spots that you see. (The reason for this is 

 that they fade in the light.) 



Make a table showing the Rp values of the 

 known amino acids. Also enter in this table the 

 Rp value of your unknown amino acid. On 

 this basis, what do you think it is? Compare 

 the chromatograms yielded by the unhydrolyzed 



