There are many reasons why there has to be a God. This is one of them.
The probability of getting a properly folded chain of one-handed amino acids, joined by peptide bonds, is one chance in 10^74+45+45, or one in 10^164 (Meyer, p. 212). This means that, on average, you would need to construct 10^164 chains of amino acids 150 units long to expect to find one that is useful.