What is "pizza crust yeast"?
It sounds like you have Fleischman's Pizza Crust Yeast (or a no-doubt quite similar product if from another manufacturer).  The relevant phrase from the Fleischman marketing web site is:


  Pizza Crust Yeast is specially-formulated with dough relaxers that
  keep the dough from pulling or snapping back when shaping it.


It is intended to make it easier to stretch the pizza dough into shape.

The yeast itself is normal instant yeast, to the best of my knowledge&mdash;the additives in the packet are what make it "pizza crust yeast".

Researching the additional ingredients other than yeast:


Sorbitan monostearate&mdash;According to Sci Toys is an emulsifier with a polar and non-polar ends:


  Sorbitan monostearate is used as an emulsifying agent in cake mixes,
  icings, baked goods, puddings, imitation whipped cream, hemorrhoid
  creams, and creams to treat dry skin.


Cooking for Engineers mentions that this helps the dough absorb the water.
l-cysteine*&mdash;is an amino acid, which is naturally occurring, and often extracted from hair or feathers.  This article from LALLEMAND explains the science in bread dough, where it acts as a reducing agent:


  During mixing the gluten in the ﬂour is stretched and pulled apart so
  that it can be reformed during prooﬁng and baking to provide the
  needed strength and structure. Reducing agents act like mixing to
  reversibly break down gluten so that once they have been used up the
  gluten reforms. This mechanism is the opposite of oxidizing agents,
  which build up gluten. Reducing and oxidizing agent

ascorbic acid*&mdash;is of course Vitamin C, and a fairly strong acid.  According to Effect of Ascorbic Acid on the Rheological Properties 
of Wheat Fermented Dough in Czeck Journal of Food Sciences, at concentrations under 0.6% it has little effect on wheat flour, so it is unlikely to have any practical effect in a full batch of pizza dough.  Its inclusion is probably (as mentioned in Cooking for Engineers) as an anti-oxidant and preservative in the packet, rather than as an active ingredient in the bread dough.
enzymes&mdash;no doubt the particular enzymes and their ratios are proprietary to the brand you have, but according to the Wikipedia article on flour treatment agents, they are used to increase transformation of starch into sugars to facilitate the action of the live yeast.  Common enzymes used include:


  
  Amylases break down the starch in flours into simple sugars, thereby
  letting yeast ferment quickly. 
  Malt is a natural source of amylase.
  Proteases improve extensibility of the dough by degrading some of the
  gluten. 
  Lipoxygenases oxidize the flour.  
  



See also this Baker's Yeast article from Cooking for Engineers which discusses various commercially available forms of yeast.



My personal opinion is that I would not buy "pizza crust yeast," since recipes are not designed for the presence of its dough conditioners.  I would rather control my dough's ingredients myself.  However, since you have the product, why not try it using the vendor's recipe?  I would be fascinated to hear how it performs.