VOL. 12 (1953) 



BIOSYNTHESIS OF GLUCOSAMINE 



17 



RESULTS 



The formation of "glucosamine". Incubation of hexose-6-phosphate with glutamine 

 and the enzyme gave rise to an increase 

 in the glutamine content. As shown in 

 Fig. I, hardly any increase took place 

 when glutamine or hexose-6-phosphate 

 were omitted. 



The results of an analysis of the 

 chemical changes occurring during the 

 reaction appear in Table I. The increase 

 in "glucosamine" was approximately 

 equal to the decrease in amide nitrogen 

 of glutamine and to the increase in glu- 

 tamate. There occurred also a small 

 increase in ammonia in the complete 

 system as well as in the controls with- 

 out glutamine. 



An experiment carried out at diffe- 

 rent temperatures appears in Table II. 

 At 37° glucosamine formation was faster 

 than at 30° in the beginning, but slower 

 afterwards. 



In many experiments it was obser- 

 ved that the enzyme solutions became 

 rapidly inactivated at room tempera- 

 ture. On the other hand, in the experi- 

 ments of Fig. I -the enzyme in the pres- 



Hours 



Fig. I. The formation of glucosamine. Incubation 

 at 30° of I mg of purified enzyme and 0.05 ml of 

 trishydroxymethylaminoethane acetate buffer of 

 pH 6.4 with substrates. Total volume, 0.2 ml. 

 Curve I, o ^<moles of hexose-6-phosphate 



+ 2 /^moles of glutamine 

 Curve 2, 2 /tmoles of hexose-6-phosphate 



-f o /tmoles of glutamine 

 Curve 3, I /imoles of hexose-6-phosphate 



-{- 5 ^moles of glutamine 

 Curve 4, 4 /anoles of hexose-6-phosphate 



+ 2 /<moles of glutamine 

 Curve 5, 4 ^imoles of hexose-6-phosphate 



+ 5 yumoles of glutamine 



TABLE I 



BALANCE EXPERIMENT 



The aliquots of the complete system taken for analysis contained: 1.3 /^moles of glutamine, 

 1.3 /imoles of glucose-6-phosphate and 0.6 mg of purified enzyme and citrate buffer. pH 6.4. Total 

 volume, o.i ml. Incubated 3 hours at 30°. 



^ "glucosa- 

 mine" 



A amide A ^H^ 



Complete system 



No glutamine 



No hexose-6-phosphate 



A glutamate 



TABLE II 



FORMATION OF "GLUCOSAMINE" AT DIFFERENT TEMPERATURES 



Complete system as in Table I. Results in /umoles. 



References p. 22. 



