I really don't know what the 'minimum' would be to kill a deer, but I do know I wouldn't hunt with that minimum as if its IS the minimum to kill deer, its too close to boarderline to not kill it.
Most 45# bows will kill a deer, and you are above the minimum you are asking about.
I personally wouldn't want to hunt will less than 45#s...cept a few of todays bows I might go 40# if I had to.