Chemical Education Journal (CEJ), Vol. 16/Registration No. 16-102/Received December 11, 2013.
URL = http://chem.sci.utsunomiya-u.ac.jp/cejrnlE.html

A New and Simple Method for Drawing of the Monosaccharide Fischer Projection Based on New Monosaccharide's Barcodes

RAHBARI Jalaladdin¹, ELAHIRAD Saeed¹, NOROOZI PESYAN Nader^2*

¹ Department of biology, Faculty of Science, Urmia University, 57153-165, Urmia, Iran
²Faculty of Chemistry, Urmia University, 57159, Urmia, Iran
E-mail: nnp403gmail.com

Abstract
In the present educational work, a new and simple method to drawing of the monosaccharide Fischer projection based on new monosaccharide's barcodes has been presented. In this method, monosaccharide column, monosaccharide visions, new barcodes for each monosaccharide (aldose and ketose) is presented and are compared with known method of Arita & Tokimatsu method. New method for the boxation of monosaccharide column and corresponding numberations are exhibited. The Table of monosaccharide is presented based on new monosaccharide barcodes. Finally, an interesting triangular diagram for aldoses and ketoses is presented based on new monosaccharide barcodes.

Keywords: Monosaccharide number, Monosaccharide vision, Monosaccharide column, Monosaccharide lines, Fischer projection, Aldose, Ketose

Contents

Introduction

Results and Discussion

(a) Introduction to monosaccharide column via known Fischer projections.

(b) Introduction to monosaccharide vision via Fischer projections.

(c) Introduction to right and left hands functions in monosaccharide column.

(d) Introduction to boxation of the right and left hands functions and its side.

(e) Introduction to numbering of boxation and its side.

(f) Introduction to monosaccharide's number (monosaccharide's barcode).

(g) Introduction to monosaccharide Table.

Monosaccharide's number recognition

(h) Drawing the Fischer linear projection.

(i) Introduction to triangular diagram for aldoses and ketoses.

Conclusion

Acknowledgements

Reference

Appendix

Introduction

Monosaccharides are polyhydroxy aldehydes or ketones having four to nine carbon atoms in their carbon chains most often, five or six [1]. Many chemists have been described new methods to alleviate the knowledge obstacle in monosaccharides. For example: the basic work of Fischer and Van't Hoff in carbohydrate chemistry [2], the use of schematic formulas as an aid to rapidly representing configurations for monosaccharides [3], binary notation to indicate the structure of carbohydrates [4], the history of the nomenclature of carbohydrates [5] have been presented.

Although the structure of carbohydrates is much more complicated than linear DNAs and protein sequences, linear systematic codes have been already proposed [6,7]. The monosaccharides, the building units of carbohydrates, have multiple stereocenters. The presences of these multiple stereocenters contribute to the rich structural diversity of carbohydrates, enabling them to serve as 'molecular (cellular) barcodes' [8]. Monosaccharide cycles (MoCycle) is an interesting method to determine the general stereochemical relationships of both D and L monosaccharides has been reported by Hunsen [8].
Arita and Tokimatsu [9] reported that the stereo parities of four chiral positions (from C5 to C2) for D-hexose and D-pentose sugars. They pointed that the corresponding parity for L-sugars can be obtained by flipping all 1 and 2. In their method, the parity 1 and 2 corresponds to right and left orientation of the Fischer projection from the bottom up, respectively. Non chiral positions are skipped and the keto group is represented by '_' to distinguish hexoses and pentoses by the same authors. The mentioned above parity description from the bottom-up is original notation (Table 1) [9].

In the present work, we have introduced a new and simple method for description of the drawing of the monosaccharide Fischer projection with using new formal barcodes, introducing monosaccharide column, monosaccharide vision, numberation side and triangular diagram for aldoses and ketoses.

Results and Discussion

This paper describes a new educational method for drawing of the monosaccharide Fischer linear projections and is useful for learning of undergraduate and graduate students and introduction to monosaccharide number and some useful aspects as below;
(a) Introduction to monosaccharide column via known Fischer projections.
(b) Introduction to monosaccharide vision via Fischer projections.
(c) Introduction to right and left hands functions in monosaccharide column.
(d) Introduction to boxation of the right and left hands functions and its side.
(e) Introduction to numbering of boxation and its side.
(f) Introduction to monosaccharide's number (monosaccharide's barcode).
(g) Introduction to monosaccharide Table.
(h) Drawing the Fischer linear projection.
(i) Introduction to triangular diagram for aldoses and ketoses.

(a) Introduction to monosaccharide column via Fischer projections

Monosaccharides divided to two classes of an aldose and ketose. Representatively, herein, we discussed about glucose as an aldose and fructose as a ketose. Herein, the perpendicular carbon chain in the Fischer linear form is called monosaccharide column. For instance, the monosaccharide column for D- and L-Fischer projections for four monosaccharides are shown as below in violet perpendicular rectangle.

Figure 1. The monosaccharide column is shown in violet rectangular.

(b) Introduction to monosaccharide vision via Fischer projections

In the monosaccharide molecule, after finding the anomeric functional group in the chain (aldehyde or ketone function), we always look at the monosaccharide column in which the aldehyde or ketone functional group points away from the viewer (Figure. 2).

Figure 2. Representatively, the side of monosaccharide vision in D-Glucose and D-Fructose.

(c) Introduction to right and left hands functions in monosaccharide column

We identify the right and left handed functions in monosaccharide column after we look at the molecule along monosaccharide vision side. According to the Figure. 3, all horizontal functions in the right and left handed of the monosaccharide column (Functions are located on the chiral carbon atoms of aldose and/or ketose) are called column right and left functions, respectively.

Figure 3. Introduction of column right and left functions.

(d) Introduction to boxation of the right and left hands functions and its side

•- The boxation of the monosaccharide column is done for its column right and left functions.
•- We bundle the right and left hand functions on each chiral center separately.
•- All H and OH functions to be bundled separately.
•- Any vicinal repeated similar functions are put in one box (Figure.4).

Figure 4. Representatively, boxation side in D- and/or L-glucose in a monosaccharide column.

(e) Introduction to numbering of boxation and its side

In Arita and Tokimatsu method [9] (see also Table 1), they pointed that the corresponding parity for L-sugars can be obtained by flipping all 1 and 2. In their method, the parity 1 and 2 corresponds to right and left orientation of the Fischer projection from the bottom to up, respectively. In our new method, the barcoding of each monosaccharide can be done based on the following items.
•- The side of numberation of boxes is the same side of monosaccharide vision.
•- All boxes contain OH and/or H function to be numbered by an integer number and primate integer number ('), respectively and these numbers assigned in green color in the monosaccharide structure formula (Figure. 5).
•- The number of the functions that are located into each box is written in the front of each own box (Figure. 5).

Figure 5. Representatively, numberation of D- and/or L-glucose and its side.

(f) Introduction to monosaccharide's number (monosaccharide's barcode)

From the numberation of monosaccharide left and right handed functions (for example in D- and L-glucose), we can obtain two triplex number (for example; two significant digits for each of D- and L-glucose). For instance, these numbers is shown for D- and L-glucose in Figure. 6 and highlighted as green color into the yellow rectangular.

Figure 6. Barcode of D- and L-glucose as representative.

(g) Introduction to monosaccharide Table

According to Figure. 6, we obtain two numbers of 21'1 and 2'11' for D- and L-glucose that are alternate integer number and primate integer number (the integer and primate integer numbers are corresponding to OH and H functions, respectively). Now, if we waiver from the primate sign, we obtain a significant number of (211) for glucose as representative. Therefore, the number of 211 is called a glucose monosaccharide's number (monosaccharide's barcode). Based on the finding of glucose monosaccharide number, all the related barcode of aldoses and ketoses were obtained and outlined in Table 2 (see also appendixes I-IV).

Therefore, from the combination of monosaccharide vision side with boxation and numberation sides, the following sign can be obtain in result (Figure. 7).

Figure 7. The parallel same sides of boxation, numberation, numeration and monosaccharide vision sides.

Monosaccharide's number recognition

As we see in Table 2, some of monosaccharides from aldose and ketose groups have the same monosaccharide's no. (For instance; glyceraldehyde and erythrulose (1), erythrose and ribulose (2), Xylose and Sorbose (111) and etc. For the clarification of each aldose's and ketose's no., let us to use a common no. in which to add the letters of A and K for the front of aldose and ketose no., respectively, as bellow;

Where, mn is the monosaccharide's number, A and K are represents of aldose and ketose, respectively.
For example: Arabinose no. = 21A Fructose no. = 21K
Threose no. = 11A Xylulose no. = 11K

(h) Drawing the Fischer linear projection via monosaccharide number

In the section (f), we discussed the conversion of Fischer projection to monosaccharide number. Now we learn the drawing Fischer projection with using monosaccharide number. On the other words, how we can use the monosaccharide number for drawing the Fischer projection.

The rules of drawing Fischer projection using monosaccharide number are as follow;
•- Characterize the kind of monosaccharide (aldose or ketose) according to monosaccharide Table (Table 2).
For example: D-Glucose no.: 211A
D-Fructose no.: 21K
•- Determine the number of carbon atoms in the monosaccharide chain.
a) In aldoses, the sum of monosaccharide no. boxes plus 2 is equal to the carbon atoms number in aldose chain skeleton (monosaccharide no. are available from Table 2), so as Equation (1);

Where; CA = Number of carbon atoms in aldose chain, b = box.
Example 1: We can write for Glucose (211A) according to equation (1); CGlucose = 2 + 1 + 1 + 2 = 6 (indicating aldohexose)
Example 2: Threose (11A); CThreose = 1 + 1 + 2 = 4C (indicating aldotetrose)
Example 3: Idose (1111A); CIdose = 1 + 1 +1 + 1 + 2 = 6C
Example 4: Lyxose (12A); CLyxose = 1 + 2 + 2 = 5C
Example 5: Allose (4A); CAllose = 4 + 2 = 6C
b) In ketoses, the sum of monosaccharide no. boxes plus 3 is equal to the numbers of carbon atoms in ketose chain skeleton as in Equation (2). Therefore,

Where; CK = Number of carbon atoms in ketose chain, b = box.
Example 1: Fructose (21K); 2 + 1 + 3 = 6C (indicating ketohexose)
Example 2: Psicose (3K); 3 + 3 = 6C (indicating ketohexose)
Example 3: Erythrulose (1K); 1 + 3 = 4C (indicating ketotetrose)
Example 4: Dihydroxyacetone (0K); 0 + 3 = 3C
c) The route of drawing Fischer projection using simple monosaccharide number.
For instance, for D-glucose, in the opposite side of monosaccharide vision, placing a hydroxyl group (OH function) at C-2 to the right (for number 1) and next OH function to the left (for number 1), then two vicinal OH (for number 2) to the right in the alternate horizontal bonds in monosaccharide chain (Figure. 8).

In the other hands, the barcode of 211A (D and/or L-glucose), the number 1 (in blue color) is the hydroxyl group in which near to the aldehyde functional group on the first chiral carbon atom in the monosaccharide column chain. The number of 2 (in red color), indicating the two vicinal OH groups to be far (from aldehyde functional group) in the left and/or right-hand of monosaccharide column (Figure. 8). Based on this rule we can draw all monosaccharide (aldose and ketose) Fischer projection from their corresponding barcode. For example: For the drawing of the Fischer projection of D- and/or L-Glucose (211A) and D- and/or L-Fructose (21K), it can be proceeding as below:

Figure 8. Drawing of Fischer projection using monosaccharide number for D-glucose and D-fructose as representative.

d) Draw the chain after determining of the number of carbon atoms in the monosaccharide chain.
d-1) In aldoses, draw CHO group as a C-1 and refer the CH2OH as a latest carbon atom (Figure. 9).
d-2) In ketoses, refer the -CO-CH2OH group as a C-1 and C-2, respectively, and CH2OH as a latest carbon atom (Figure. 9).

Figure 9. An aldohexose and a ketohexose chain skeleton.

d-3) Look at the molecule in monosaccharide vision side.
d-4) Locate the hydroxyl and/or H functions in the chain with using monosaccharide number.

(i) Introduction to triangular diagram for aldoses and ketoses

Interesting triangular diagrams of aldoses and ketoses are shown in Figure. 10 and Figure. 11, respectively. According to these diagrams and appendixes I-IV, the learning and remember of monosaccharide's number to be easy in this method.

Figure 10. Triangular diagram of aldoses based on tree diagram.

Figure 11. Triangular diagram of ketoses based on tree diagram.

Conclusion

In summary, a new and simple method to drawing of the monosaccharide Fischer projection based on new monosaccharide's barcode has been presented. The new monosaccharide's barcode caused to become easy learning and mnemonic of the monosaccharide's Fischer projection. The drawing of any monosaccharide stereo structure (aldose and/or ketose) to be very easy according to new barcodes and is the advantage of this new method.

Acknowledgements

We gratefully acknowledge the Research Council of Urmia University.

Reference

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Appendix I
Tree diagram of D-ketoses and their codes (Codes of D- and L- stereoisomers are the same).

Appendix II
Tree diagram of L-ketoses and their codes.

Appendix III
Tree diagram of D-aldoses and their codes (Codes of D- and L- stereoisomers are the same).

Appendix IV
Tree diagram of L-aldoses and their codes.