"All enzymes are not proteins." This statement is justified by:
Ribozymes are RNA molecules with catalytic activities, which acts upon phosphodiester bonds in RNA & cause its hydrolysis lintron splicing event. RNAs are not protein, but meet all the classic criteria of enzymes therefore all enzymes are not protein
All enzymes do not follow the Michaelis Menton hypothesis
RNAs act as ribozymes
Antibodies take pa in the catalysis of many reactions
Metals are involved in attachment to enzymes and catalysts