Peptidy transferase is RNA enzyme formed by 23Sr rRNA of large subunit of 70s ribosme.

Answer

### Step-by-Step Solution:

1. **Understanding Peptidyl Transferase**:
- Peptidyl transferase is an enzyme that plays a crucial role in protein synthesis. It is responsible for catalyzing the formation of peptide bonds between amino acids, which is essential for the growth of the polypeptide chain.

2. **Location of Peptidyl Transferase**:
- This enzyme is located in the large subunit of the ribosome. In prokaryotes, such as bacteria, the ribosome is referred to as a 70S ribosome, which is composed of two subunits: the 30S and the 50S subunits.

3. **Composition of the Ribosomal Subunits**:
- The 30S subunit contains 16S rRNA, while the 50S subunit contains both 23S rRNA and 5S rRNA. It is the 23S rRNA that possesses the peptidyl transferase activity.

4. **Function of 23S rRNA**:
- The 23S rRNA in the large subunit serves as a ribozyme, meaning it has enzymatic activity despite being an RNA molecule. It catalyzes the peptide bond formation between amino acids during the translation process.

5. **Role in Protein Synthesis**:
- During translation, as the ribosome moves along the mRNA, the peptidyl transferase activity of the 23S rRNA facilitates the addition of amino acids to the growing polypeptide chain, thus playing a vital role in protein synthesis.