I would always spin down tubes containing liquid before opening them to bring all sample to the bottom. Regarding vortexing, I would be very cautious with any protein sample. In case you want to make sure the sample is well mixed, I would just snip it and then spin down, or first spin and then carefully pipet up and down without forming air bubbles.
I agree with @Heide Marie Resch with regard to avoid vortexing the protein samples like antibodies or enzymes. Vortexing can affect the quality of proteins and denature it. Short spins can be performed, just to bring all the sample from walls to bottom. For mixing, you can perform a gentle pippete in and out.