I am using Angular with Bootstrap. Here is the code for reference:
It's hard to tell for sure without a fiddle but looking at the angular.js code it does not replace classes - it just adds and removes its own. So any bootstrap classes (added dynamically by bootstrap UI scripts) should be untouched by angular.
That said, it does not make sense to use Bootstrap's JS functionality for validation at the same time as Angular - only use Angular. I would suggest you employ the bootstrap styles and the angular JS i.e. add the bootstrap css classes to your elements using a custom validation directive.