Unfortunately, {HEAD ~ discrepancies} among recent reports have added to {TAIL ~ the general uncertainty} as to the true enzymatic function for this family of proteins 
added to
Unfortunately , { HEAD ~ discrepancies } among recent reports have added to { TAIL ~ the general uncertainty } as to the true enzymatic function for this family of proteins
OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH