max float represented in IEEE 754
The exponent 11111111b is reserved for infinities and NaNs, so your number cannot be represented.
The greatest value that can be represented in single precision, approximately 3.4028235×1038, is actually 1.11111111111111111111111b×211111110b-127.
See also http://en.wikipedia.org/wiki/Single-precision_floating-point_format