Ligases make bonds, thereby hydrolysing an energy rich bond.

1

• Ligases make bonds, thereby hydrolysing an energy
  rich bond.
• Subclasses Which bond is formed?

2
(Hydrolase)

• Examples for classification

(Transferase)
(Hydrolase)
(Ligase)
(Isomerase)
3
Essential groups amino acid side chains,
non-covalent intermediates Asp Argininosuccinate
synthetase
4
Asp Argininosuccinate synthetase
5
Asp Argininosuccinate synthetase
6
Asp Argininosuccinate synthetase
7

• Essential groups Amino acid side chains,
  covalent intermediates
• aa ?

8

• Essential groups metals
• Mg2 Adenylosuccinate synthetase

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• Mg2 Adenylosuccinate synthetase
• GTP IMP L-Aspartate lt---gt
• GDP Pi Adenylosuccinate (AMPS)

10
Mg2 is coordinated by the g-phosphate and
enables the nucleophilic attack on the
phosphorous atom. Asp13 increases
nucleophilicity of the 6-O of IMP.
11
Mg2 is coordinated by the phosphate and enables
the nucleophilic attack of the amino group. Asp
13 pulls a proton off the purine.
12
Gramicidin synthetase