Nucleic Acids in Chemistry and Biology

RNA Structure and Function 279

N

N

N

N

NH

2

O

O

OH

O C

O

CH

R^1

HN

O

N

N

N

N

NH

2

O

O

OH

O C

O

CH

R^2

NH

3

N

N

N

N

NH

2

O

O

OH

O C

O

CH

R^1

HN

O

N

N

N

N

NH

2

O

O

OH

O C

O

CH

R^2

NH

2

N

N

N

N

NH

2

NH

2

NH

2

O

O

OH

O C

O

CH

R^1

R^1

R^2

R^2

NH

O

N

N

N

N

O

O

O HO

O C

HC

H^2 N

N

N

N

N

O

O

OH

O C

O

CHNH

O

N

N

N

N NH

2

O

O

O HO

O C

HC

H^2 N

N

N

N

N

NH

2

O

O

OH

O C

O

CH

R^2

NHC

O

CH

R^1

C

O

N

N

N

N

NH

2

O

O

OH

OH

H

H

• T

1

2

±T

3

4

Figure 7.31

The peptidyl transfer reaction. The terminal amino group (red) of the incoming tRNA in the A-site is deprotonated and attacks t

he

activated ester at the growing end of the nascent peptide chain (step 2). After resolution of the resulting tetrahedral intermediate (steps 3 and 4), the nascent chain is transferred to the tRNA in the A-site (see Figure 7.30). This peptidyl-tRNA then moves to the P-site so that the process can begin again with a new charged tRNA