O  15.99940 ;     carbonyl oxygen (C=O)
   OM  15.99940 ;     carboxyl oxygen (CO-)
   OA  15.99940 ;     hydroxyl, sugar or ester oxygen
   OE  15.99940 ;     ether or ester oxygen
   OW  15.99940 ;     water oxygen
    N  14.00670 ;     peptide nitrogen (N or NH)
   NT  14.00670 ;     terminal nitrogen (NH2)
   NL  14.00670 ;     terminal nitrogen (NH3)
   NR  14.00670 ;     aromatic nitrogen
   NZ  14.00670 ;     Arg NH (NH2)
   NE  14.00670 ;     Arg NE (NH)
    C  12.01100 ;     bare carbon
  CH0  12.0110  ;     bare sp3 carbon, 4 bound heavy atoms
  CH1  13.01900 ;     aliphatic or sugar CH-group
  CH2  14.02700 ;     aliphatic or sugar CH2-group
  CH3  15.03500 ;     aliphatic CH3-group
  CH4  16.04300 ;     methane
 CH2R  14.02700 ;     CH2-group in a ring
  CR1  13.01900 ;     aromatic CH-group 
   HC   1.00800 ;     hydrogen bound to carbon
    H   1.00800 ;     hydrogen not bound to carbon
  DUM   0.00000 ;     dummy atom, no idea what the mass should be. PT3-99
    S  32.06000 ;     sulfur
 CU1+  63.54600 ;     copper (charge 1+)
 CU2+  63.54600 ;     copper (charge 2+)
   FE  55.84700 ;     iron (heme)
 ZN2+  65.37000 ;     zinc (charge 2+)
 MG2+  24.30500 ;     magnesium (charge 2+)
 CA2+  40.08000 ;     calcium (charge 2+)
    P  30.97380 ;     phosphor
   AR  39.94800 ;     argon
    F  18.99840 ;     fluor (non-ionic)
   CL  35.45300 ;     chlorine (non-ionic)
   BR  79.90400 ;     bromine (non-ionic)
 CMET  15.035   ;     CH3-group in methanol (solvent)
 OMET  15.9994  ;     oxygen in methanol (solvent)
  NA+  22.9898  ;     sodium (charge 1+)
  CL-  35.45300 ;     chlorine (charge 1-)
 CCHL  12.011   ;     carbon in chloroform (solvent)
CLCHL  35.453   ;     chloride in chloroform (solvent)
 HCHL  1.008    ;     hydrogen in chloroform (solvent)
SDMSO  32.06000 ;     DMSO Sulphur (solvent)
CDMSO  15.03500 ;     DMSO Carbon (solvent)
ODMSO  15.99940 ;     DMSO Oxygen (solvent)
 CCL4  12.011   ;     carbon in carbontetrachloride (solvent)
CLCL4  35.453   ;     chloride in carbontetrachloride (solvent)
 FTFE  18.99840 ;     fluor in trifluoroethanol
 CTFE  12.01100 ;     carbon in trifluoroethanol
CHTFE  14.0270  ;     CH2-group in trifluoroethanol
 OTFE  15.99940 ;     oxygen in trifluoroethanol
CUREA  12.01100 ;     carbon in urea
OUREA  15.99940 ;     oxygen in urea
NUREA  14.00670 ;     nitrogen in urea
   SI  28.08	;     silicon
 MNH3   0       ;     Dummy mass in rigid tetraedrical NH3 group
   MW   0       ;     Dummy mass in rigid tyrosine rings