Vitamin C and immuneSystem

8/14/2019 Vitamin C and immuneSystem

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Confirmation of Pauling's Theory that VitaminC Improves Immunity to InfectionsG . N . R A M A C H A N D R A N

Indian Institute o Science, Bangalore 560 12, India and Fogarty InternationalScholar, National Institutes o Health, Bethesda, Maryland 2 14 , U.S .A .

Dedication to my Revered GuruProfessor Linus PaulingLinus PaulingIn chem ical bondingFollows for all m atte r,Their na ture and character

Is a name to conjure with,And w hatever forthwithBoth inanima te and aliveAnd how they will behave.

His great alpha helix,Th at opened the pathFor the solution of structuresOf all biopolymers,

Is a star that will adornT he firmam ent of Science,For it has revealed to b iologists

Com pletely new ways.As a submission to this m aster,

I have todayPrepared a short paperFollowing his wayWh ich shows tha t his conjectureOn Vitamin C1s surely a tru e pictureOf w hat is expected to be.

International Journal o Q u a n t u m Chemistry: Quantum Biology Symposium 5. 15-20 I 978c 1978 by Joh n Wiley Sons. Inc. 0360 8832/78/0005 00I 5 0lOO


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Hydroxyproline e ntial for stabilii ofCOLLAGEN

triple helical slructure

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COMPLEMENThas in it two ropes oflriple helical peptidescontaining hydroxyproline

AbstractIt is pointed out th at the co mplemen t Clq, associated with the imm une response system. has apart containing about 80 residues with a collagen-like sequence, with Gly at every third location

and having also a number o f Hyp and Hyl residues in locations before Gly. and th at it takes thetriple-helical conformation characteristic of collagen. As with collagen biosynthesis. ascorbic acidis there fore expected to be required for its production. Also, collagen itself, in the extracellular matrix.is connected with the fibroblast su rfac e protein FSP). whose absence leads to cell proliferation,and whose add ition leads to suppression o f malignancy in tissue culture. All these show the greatimportance of vitamin C for resistance to diseases, an d even to cancer. a s has been widely advocatedby Pauling1. Paulings Idea Regarding Vitamin C

Linus Pauling has wideLy advocated that vitamin C improves the humanbodys resistance to diseases. Although physicians have been prescribing ascorbicacid a s a regular dietary supplement for good health, there has been skepticismamong medical researchers about the claims made by Pauling.Th e purpose of this short paper is to show that a connection between vitaminC and .imm une response can, in fact, be established in term s of recently discov-ered results on the biosynthesis of collagen. This connection occurs u i thearguments set forth in the form of a flow chart in Figure 1 We shall considerthese briefly below.IMMUNOGLOBULINE lG l

AMACHANORAN PORTERBo th COLLAGEN and COMPLEMENT

have a triple helical structureend hydroxyproline residues

A

Hence Vitamin C improvesImmune Response

PAULING IS VINDICATEDFigure I . Importance of vitamin C.

B


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C O N F I R M A T I O N O F PAULINGS T H E O R Y 17

2. Collagen Structure and BiosynthesisThe molecular structure of collagen has been studied in the authors laboratoryfor the last 25 years, during which the essentials of the triple-helical structu re,

established in 1954- 1955, have been supplemented by fu rther refinements. Themain theoretical result that has reference to vitamin C was the discovery in 1971of the role played by hydroxyproline in the stabilization of the collagen structure,by means of hydrogen bonds involving the O H group of hydroxyproline [ 1,2].H ydroxyproline residues are special for collagen, and are produced from prolineswhich are transcribed from the genetic code), after their incorporation in thepeptide chain [3,4]. The hydroxylation process is facilitated by the enzymeproline hydroxylase , whose activity requires ascorbic acid as cofactor see Ref.5). I n fact, the very name ascorbic acid arises from its cura tive and preventiveaction against scurvy, which is essentially a disease involving collagen biosyn-thesis see Ref. 6 .Before we pass on to the relevant properties of the im mune response system ,it is necessary to m ention a few other essen tial featu res of the collagen primarysequence. Thus, the collagen triple helix can be stabilized by hydrogen bondsbetween the different chains only if glycine occurs a t every third position in thesequence, is in fact true for the collagen sequences see Ref. 7) . This type ofrepetitive occurrence of G ly was the essence of the triple-helical structu re ofcollagen worked out by Ramachand ran and Kartha [8], and they showed at thesam e time that the imino acid residues Pro and Hyp, in which the n itrogen atomis connected to the a-carbon atom by the rigid pyrolidine ring, can be readilyaccommodated i n the structure. Many later studies, both theoretical and ex-perimental, have shown that both Pro and Hyp lend stability to the collagenprotofibril by virtue of their side-chain ring, which makes the dihedral angle6 estricted to values near -60 see Ref. 2). However, the fact tha t Hyp lendsadded stability by virtue of its hydroxyl group became clear only in 1970s whenit was shown from stereochemical considerations by Ramachandran et al. [ I ]and confirmed by the experim ents of several groups e.g., Berg and Prockop [9];Jimenez et al. [ l o ] , and Fessler and Fessler [ l 11). Therefore, it is w orthwhilementioning th at this Hyp side chain m ust occur immediately previous to Glyin the peptide chain, e.g., at location Y in the sequence -Gly-X-Y-Gly-X-Y- a. Further, the hydroxyl groups in the five-membered ring mustbe 4-trans for the hydrogen bonds to be made, a fact which is also found to beactually so in the collagen primary sequence certainly in type 1 collagen, whichis the m ost common one), see Piez [7].

So also, the unusual am ino acid residue hydroxylysine H yl) is also charac -teristic of collagen and occurs at the location Y only, and is produced from lysineresidues after incorporation in the peptide chain by a special enzyme lysinehydroxylase, which also apparently requires ascorbic acid as cofactor see Ud-enfriend [4] and Prockop et al. [ 5 ] . The Hyl chains are invariably glyco-sy la ted


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18 R A M A C H A N D R A N

3. Relevant Fac ts About the Immune Response Syste mIt is well known tha t the recognition of invading pathogenic organism s is madeby the so-called immunoglobins, which produce antigen-antibody complexes.Af ter this initial step, the complex activates a series of members of comple-ment, a name collectively given to the protein components of blood serum thatare involved in an avalanche process that finally leads to a hole in the pathogencell surface, thus killing it. The imm unoglobulins have been widely studied, butthe n atur e and action of the complement molecules have been relatively muchless investigated. However, it is interesting that the primary sequence of the firstcomponent Clq is known.Soon after the time when the role of Hyp in the collagen protofibril was workedout in 1971, the author became aware of the fact that work done at the laboratoryof Porter in Oxford had shown tha t the complement Clq had an unusually largepercentage of Gly residues and tha t it also had both H yp and Hyl residues. Thisimm ediately suggested to him tha t this protein m ay have a triple-helical struc-tu re , and he wrote to this effect to Porter, asking for information abo ut the se-quence. H e then lost interest in this and learnt about the sequence only whenhe received the manuscript of the chapter by Piez [7] in 1975 in which a 95residue sequence determined at Oxford [ 121 was reported. In this sequence,nearly 80 of the residues had the ordered Gly-X-Y sequence characteristic

of collagen, and further Hyp occurred at the location Y five times and Hyl fourtimes, also at location Y, exactly as in collagen. In fac t, the authors conclusionfrom the reported sequence tha t the complement Clq has the rod-like collagentriple-helical struc ture was confirmed, when he was shown electron microscopicpictures of this material taken at O xford in July, 1977.4. Relevance of Vitamin C to Immunity

Although all the above facts were clear and were repeatedly discussed by theauth or with various scientists during the last six months and m ore, and even thestateme nt A from Figure 1 was discussed with them, the conclusion marked Bin Figure was completely hidden and become evident only much later. In fact,this becam e obvious to the mind of the author only as a result of a sharp stimulus,which came during a breakfast discussion with Si r George Picketing RegiusProfessor of Medicine a t Oxford) a t the Fogarty International Center in January,1978 . Pickering reasserted strongly the skepticism mentioned in the first para-graph of Sec . 1, and said tha t Pauling was not being scientific. Immediately, theword Oxford associated with Pickering evoked the following responses:Oxford- Porter-Complement-H ydroxyproline

-Collagen biosynthesis-Vitamin C-Paulingand the remarkable expectation B, from Figure 1 followed by virtue of the factsstated in the other blocks in Figure 1.


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C ONF I R M AT I ON OF PAULINGS TH EO RY 19

5. Concluding RemarksThe author is fully aware of the fact that the absolute requirem ent of ascorbicacid for the hydroxylation process in collagen is probably not conclusive, but

in uiuo studies clearly implicate the need of vitamin C for collagen synthesis andshow the occurrences of collagen disease in its absence [ 6 ] .Hence, since com-plement C is essential for the immune response, its production in the triple-helical form in the body should also be expected to require vitamin C, so thatstatement B is expected to be certainly valid.It is hoped that the biosynthesis of com plementC n the presence and absenceof ascorbic acid would be carefully studied and th at the correlation betweenimmunity and the adm inistration of vitamin C could be sys tematically investi-gated.Further, it is well known th at collagen occurs not only in connective tissue,but in practically every tissue. Hence, vitamin C, which seems to be essentialfor the biosynthesis of collagen, is an absolute requirement for good health.Again, the recently discovered fibrob last su rface protein, w hich is found tobe deficient in malignant tissues, and whose addition controls cell proliferationin tissue culture, is known to bind the cell surface to collagen in the matrix [131.Hence vitamin C may play an im portan t part even in the resistance of cells tocancer-producing tendencies, as has been claimed by Pauling.

AcknowledgmentsThe author wishes to thank the N ational Institutes of H ealth for inviting himas a Fogarty Sc hola r, which gave him the unique opportun ity of discussing hispurely theoretical ideas in molecular biophysics with em inent prac tical scientistsand medical doctors and enabled him to arrive a t the interesting result reported

in this paper.

Bibliography[I ] G. N. R amachandran, M. Bansal, and R. S. Bhatnagar, Biochim. Biophys. Acta 322, 1661973).[2] G. N . Ram achand ran and C. Ramakrishnan, in Biochemistry o Collagen, G. N. Rama-

chandran and A . H. Reddi, Eds. Plenum, New York, 1976), p. 45.[3] M. R. Stet ten, J . Biol. Che m. 181.31 1949).[4] S Udenfriend, Science, 152, 1335 1966).[5] D. J . Prockop, R. A. Berg, K. 1. Kivirikko, and J . Uitto, in Biochemistry o Collagen, G. N .[6] C. M. Lapitre and B Nusgens, in Biochemistry of Collagen, G . N. Ramachandran and A.[7] K. A. Piez, in Biochemistry of Collagen,G. N. Ramachandran and A . H eddi, Eds. Plenum,[8] G. N. Ramachandran and G. Kartha, Nature Lond.) 174,269 1954).191 R. A . Berg and D. J . Prockop, Biochem. Biophys. Res. Commun. 52, I15 1973).

Ramachandran and A. H. Reddi, Eds. Plenum, New York, 1976). p. 163.H. Reddi, Eds. Plenum, New York. 1976). p. 377.New York, 1976), p. I


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20 RAMACHANDRAN

[lo] S. Jiminez. M Harsch, and J Rosenbloom, Biochem. Biophys. Res. Commun. 52, 1061973).

[ ] L I Fessler and J . H. Fessler, J. Biol. Chem. 249,7637 1974).[ 121 K Reid, Biochem. J 141, 189 1974).[ 131 Symposium Proceedings, Ann. N . Y . Acad. Sci. to be published.Received March 29, 1978

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Vitamin C and immuneSystem