Mass spectrometry data analysis of compounds

The molecular mass of the compound is 298.16 Da because this m/z spectrum is calculated under positive ionization conditions and the ions are singly charged and it is dominant in m/z 299.16. Since the charge is 1, the molecular mass is

299.16-1 = 298.16 Da

B ) What is the extremum at m/z 300.16?

The m/z at 300.16 shows a lower strength of ions and the C12 atom has been replaced by the of course happening C13 isotope. This isotope is one Da higher than the C12 atom in given m/z graph as the charge is 1 ( singly charged ) .

degree Celsius ) Theoretical, Monoisotopic mass of C18H22N2S

Monoisotopic Mass of C18H22N2S= ( 12*18 ) + ( 1.0078*22 ) + ( 14.0031*2 ) + ( 31.9721*1 )

= 216+22.1716+28.0062+31.9721

= 298.1499 Da

Therefore the Monoisotopic mass of the compound is 298.1499 Da.

Question 2.

a ) What is the molecular mass of the sample?

The molecular mass of the given sample with positive electrospray ionization spectrum is 452.3 Da.

B ) Suggest the beginning of the extremum at m/z 475.2.

The extremum at m/z 475.2 suggests that some molecules in the spectrum are being ionised by add-on of Na+ ion because the extremum at m/z 475.2 is about 23 Da higher than the expected molecular mass ( 475.2- 452.3=22.9 which is about 23 Da ) .

Question 3.

a ) Explain the difference between the bunch of ions at ca. m/z 574-6 and those at ca. m/z 461-462.

The m/z 574.3,575.3,576.3 signifies that the ions at these extremums are singly charged because the difference is 1 Da ( 575.3-574.3= 1, 576.3-575.3=1 ) and the m/z 461.4 shows a difference of 0.5 Da ( 461.9-461.4=0.5, 462.4-461.9=0.5 ) which suggests that the ions are double charged.

B ) What are the molecular multitudes of the two peptides?

The molecular mass at m/z 461.4 is 460.9 Da ( 461.4-0.5= 460.9 ) because it is double charged and the molecular mass at m/z 574.3 is 573.3 Da ( 574.3-1=573.3 ) since it is singly charged.

Question 4.

a ) Calculate the mean molecular mass of the protein.

The protein sample here give rise to multiple charged molecular ions. The molecular mass at each extremum demand to be calculated with the expression

m/z= ( MW+nH+ ) /n

where MW is the molecular weight

N is the figure of charge

H+= 1.0079

m/z is the mass to bear down ratio of the extremum

At the charge +3

1318.3= ( MW + 3*1.0079 ) /3

MW = 3954.9-3.0237

MW = 3951.8763 Da

At the charge +4

MW= ( 988*4- 4*1.0079 )

= 3950.7681 Da

At the charge +5

MW= ( 799*5-5* 1.0079 )

= 3989.9605 Da

At the charge +6

MW= ( 666.1*6- 1.0079*6 )

= 3990.5526 Da

Average Molecular mass = ( 3951.8763+ 3950.7681+3989.9605+3990.5526 ) / 4

= 3970.789 Da

Question 5.

a ) What do the ions at m/z 72.08 represent?

The ions at m/z 72.08 represent the presence of alanine in the peptide as the molecular weight of alanine is 71 Da which is about equal.

B ) What do the ions at m/z 175.12 represent?

The ions at m/z 175.12 represent the presence of Cysteine in the peptide because the difference of 175.12 and 72.08 is 103.04 which is about equal to the molecular mass of Cysteine ( 103 Da ) .

degree Celsius ) The Amino acid sequence is:

This sequence is obtained by deducting the m/z ratios

For illustration: 246-175= 71- Angstrom

333-246= 87- S

480-333=147- F

627-480= 147 -F

684-627= 57- G

813-684= 129- Tocopherol

942-813= 129-E

1056-942 = 114- N

1171-1056= 115- D

1285-1171= 114-N

1384-1285= 99- V

Therefore the amino acid sequence is ASFFGEENDNV

vitamin D ) Give more possibilities with mass difference of 186.

The possibilities are

I ) 813.40 and 627.34 and their difference is 186.06 which is about equal.

two ) 684.37 and 497.21.

vitamin E ) Why is trypsin used?

Trypsin is normally used in mass spectrometric analysis because every proteolytic component used in the analysis contain a basic arginine or lysine residue and this trypsin helps in spliting the peptide bonds at the carbonyl side of lysine or arginine.

Question 6.

The amino acid sequence is:

The sequence found with differences between the alternate extremums like

148-205, 352-205, 449-352,548-449,651-548,764-651 gave the sequence

GFPVCI ( L )

The following set say 288-175,391-288,491-390,587-490,734-587,791-734 gavethe sequence

I ( L ) CVPFG

These sequences are precisely the contrary of each other.

Question 7.

a ) Yes the Mass spectrometric informations confirms the alterations because the Val which has the molecular mass 99.1 is replaced by Leu which is 113.1 and their difference is 13. The Ile which has the molecular mass 113.1 is relaced by Asn which is 114 and their difference is 1.

So the entire difference in the mass is 14+1= 15 District attorney

Now when you see it is given that deliberate mass of FBP aldolase is 37,964.3 Da and the mass found utilizing Mass spectroscopy is 37,979.3 Da and their difference is 15 Da which indicates that the mass spectroscopy confirm the alterations.

B ) Overall mass difference of the derived merchandise:

The derived equation is given as, RNH.CH.CH2OH.CH2.O.P=O. ( OH ) 2

Lysine ( NH.CH. [ ( CH2 ) 4NH2 ] .CO ) + C3H8O5P = C6H14N2O2 + C3H8O5P = C9H22N2O7P

Molecular mass of C9H22N2O7P =

= ( 9*12.0110 ) + ( 22*1.0079 ) + ( 2*1 ) + ( 7*15.9994 ) +30.9738

=275.2424 Da

Therefore the overall mass difference = 275.2424 aa‚¬ ” 170 = 105.2424 Da.

degree Celsius ) Which Aldolase mutation reacts with DHAP?

K238A aldolase mutation reacts with DHAP.

vitamin D ) Which Lysine is responsible for enzyme activity, K236 or K238?

The Lysine K238 is responsible for enzyme activity.

vitamin E ) The other method for finding which lysine is the active site is peptide mass fingerprinting, tandem mass spectroscopy and even DNA sequencing methods utilizing limitation enzymes can besides be used.