I am interested in purchasing a lot in Houston, Texas for commercial
use, however, there is an existing deed restriction that states that
all lots within the subdivision be used for single-family
residentials.

The deed restrictions has the following section:

"These convenants are to run with the land and shall be binding on all
parties and all persons claiming under that for a period of twenty
five years from the date these convenants are recorded, after which
time said convenants shall be automatically extended for successive
periods of 10 years unless an instrument signed by a majority of the
then owners of the lots has been recorded, agreeing to change said
convenants in whole or in part.  Provided, however, that 51% of the
lot owners may amend or change these restrictions at any time."

These convenants were recorded in the 1960's but apparently is still
active and enforcable.

Is it possible for me to exclude my lot from these convenants?  If so,
how would I go about doing it?  Are there any other regulations that
would bar the lot for commercial use (there is no zoning in Houston)?

Yo yeh the convenants still apply in the subdivision. any of the other
landholders within the subdivision can enforce the convenant and stop
you from using the lot for commerical, not the town but the other land
owners in the subdivision have the right, they can get a court order
to enforce the  deed restriction even have you tear down a commerical
building

sounds like if when one of those ten years are up you can get 51% of
the land owners to sign off to allow your commerical then ok but when
is the next ten year break comming up