The earliermethod for determining the molecular weight of proteins was based on chemical analysis. The following composition of proteins were found :
Haemoglobin: 0.335% Fe
Cytochrome protein: 0.376% Fe
Peroxidase enzyme : 0.29% Se
The mole % of Se in the enzyme peroxidase is (at. mass of Se = 78.96)

Options

A. `2.16 xx 10^(-3)`
B. `2.7 xx 10^(5)`
C. `3.67 xx 10^(-3)`
D. `1.83 xx 10^(3)`

Explanation

To find the mole percent of selenium (Se) in the enzyme peroxidase, we can follow these steps:

### Step 1: Understand the given data
We know that the composition of selenium in peroxidase is given as 0.29%. This means that in 100 grams of the enzyme, there are 0.29 grams of selenium.

### Step 2: Convert the percentage to grams
Since we are considering 100 grams of peroxidase, the mass of selenium in this sample is:
\[ \text{Mass of Se} = 0.29 \, \text{g} \]

### Step 3: Calculate the number of moles of selenium
To find the number of moles of selenium, we use the formula:
\[ \text{Number of moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]
Given that the atomic mass of selenium (Se) is 78.96 g/mol, we can calculate the number of moles of selenium:
\[ \text{Number of moles of Se} = \frac{0.29 \, \text{g}}{78.96 \, \text{g/mol}} \]
\[ \text{Number of moles of Se} = 0.00367 \, \text{mol} \]

### Step 4: Calculate the total number of moles in the enzyme
Next, we need to find the total number of moles in 100 grams of peroxidase. However, we do not have the molecular weight of peroxidase. For the sake of this calculation, we can assume that the molecular weight of peroxidase is significantly larger than that of selenium, but we will use the mass of the peroxidase to find the mole percent directly.

### Step 5: Calculate the mole percent of selenium
The mole percent of selenium is calculated using the formula:
\[ \text{Mole percent of Se} = \left( \frac{\text{moles of Se}}{\text{total moles in 100 g}} \right) \times 100 \]
Since we are considering 100 g of peroxidase, the total number of moles can be approximated based on the molar mass of the protein (which we will denote as M). The mole percent can be expressed as:
\[ \text{Mole percent of Se} = \left( \frac{0.00367}{\frac{100}{M}} \right) \times 100 \]
This simplifies to:
\[ \text{Mole percent of Se} = \left( \frac{0.00367 \times M}{100} \right) \times 100 \]
\[ \text{Mole percent of Se} = 0.00367 \times M \]

### Step 6: Final Calculation
Assuming a hypothetical molecular weight of peroxidase (for example, 30,000 g/mol), we can plug it into the equation:
\[ \text{Mole percent of Se} = 0.00367 \times 30000 \]
\[ \text{Mole percent of Se} = 110.1\% \]

However, since we are looking for the mole percent relative to the total moles of the protein, we would need the actual molecular weight of peroxidase to finalize this calculation.

### Conclusion
Without the exact molecular weight of peroxidase, we cannot provide a definitive mole percent. However, the method outlined above will allow you to calculate the mole percent once the molecular weight is known.