[...]... monamino acids, CO—OH Aspartic acid / \ NH CH,—CH / HO—OC CH —CH 2 HO- -OC Monobasic diamino 2 CO— OH Glutamic acid 2 -CH \NH, acids, CO—OH Arginine NH \ C—NH NH 2 CH ,- / -CH,— CH,— CH \ NH 2 Can Science Explain Life? 14 NH Ornithine CO—OH 2 \CH —CH>—CHo—CH / 2 NH CO—OH 2 NH Lysine 2 / \ —CH>—CHo— CH —CH CHo 2 NH, Hydroxy- and Thio-amino acids: CO—OH HOCH —CH Serine 2 NH 2 CO— OH H Hydroxyglutamie acid... without which - Fig la — Fig, I o life lh is indis- incon- Spirazines 27 r/5 id I Q 5 ceivable, the chemical structure of living matter from which such life processes seem to originate must possess the two following characteristics (1) It must be of such a nature that the process : of growth by the formation of peptide linkings with amino acid molecules can take place con- Can Science Explain Life? 28 Fid... distinction should be made between two-dimensional complexity and three-dimensional complexity Although it seems impossible to explain if we assume that protomaterials possess three-dimensional complasmic plexity, yet it seems comparatively easy to explain these processes if we assume that they growth and reproduction Can Science Explain Life? 26 possess only two-dimensional complexity and that the... cleavage products a mixture of 11 Can Science Explain Life? 12 amino acids or their anhydrides (diketopiperazines), which may be represented generally as follows : H CO—NH CO— OH / -CH \NH About or 2 / —CH \CH\NH—CO / thirty of these amino acids or their anhy- drides have been isolated, the structural formulas of the more important ones being as follows : The Chemical Basis of Life CH Leucine 13 CO—OH 3 \CH—CH,—CH... Guanine Adenine Cytosine \ Thymine, Lecithin CH CH 3 R"CO 3 O O -P— O— CHo— CH— CH O O CH 3 H K'CO 2 26.0 18 Can Science Explain Life? cautiously because it has never been proved that amino acid molecules exist as such in proteins, even in peptide combination As will be explained in the subsequent chapters, they probably originated as torn-off fragments which became dislodged from the fabricated protein... polypeptides or ring structures known as diketopiperazines : 3 NH —CHE^CO—OH = NH —CHE^CO—NH—CHE—CO—NH—CHEr-CO—OH + 2 H 0; CHEr— CO NH —CHEr—CO—OH = / \ + 2 H 0 NH NH \CO—CHE/ 2 2 2 2 2 2 Numerous methods for preparing polypeptides have been devised by Emil Fischer and his col- Can Science Explain Life? 20 laborators in Germany, and molecules containing as many as nineteen amino acid groups have been... highly improbable How- ever, the chemical structures of the solid or colloidal protoplasmic materials which have been subjected to hydrolysis may not be identical with the molecular structures of synthetically prepared polypeptides, even though they may both contain peptide linkings, and with our present scanty knowledge of protein structure we would not be 22 Can Science Explain Life! assuming, without... par- The persistence with which living organisms devour every bit of food material within reach and invade the entire earth's surface with their progeny shows that they must possess within ent will the chemical structures of their tissues trivance which some con- is definitely superior to ordinary chemical forces and which can function in a man- The Chemical Basis of Life 23 ner unknown to chemical science. .. substances should also be given Can Science Explain Life 16 CO—OH Aspargine / \ NH CH —CH / 2 NH —CO 2 2 CO—OH Glutamine / CH —CH —CH / \ NH —CO NH, 2 2 2 CO—OH Creatine / H—CH \N / CH C=NH NH I 2 3 NH—CO Uric acid CO C—NEX CO NH—C—NH/ Plant nucleic acid \ / d-Kibose acid I J /4 (Phosphoric Guanine CjtosZ \ Uracyl \ ) / Animal nucleic acid \ / / Phosphoric / Desoxy- I acid I ribose / \ / I I A \ Guanine... HO—OC NH 2 Cystine 2 2 2 2 Glutathione (y-glutamylcysteylglycine) CO—OH / HO—OC \ CH CH— CH —CH 2 NH 2 2 CO S/ 2 NH NH — ^CH—CH SH 2 CO The Chemical Basis of Life 15 Heterocyclic amino acids, CO— OH Proline / CH —CH / \ NH CH 2 2 / CH 2 CO—OH Hydroxyproline CH —CH y 2 \ NH HOCH \/ CH Histidine CO—OH NX NH CO—OH \ CHo—CH / C— H XN 2 NH- -CH Tryptophane CH- 2 H IN / \ -C // // \ C/ / \ CH==CH CH C—CH —CH . // C—C NH 2 H H / CO— OH / CH,—CH HO—OC NH 2 HO- -OC CH 2 — CH 2 -CH CO— OH NH, NH 2 C— NH CH ,- -CH,—CH,— CH CO—OH / NH 2 14 Can Science Explain Life? Ornithine NH 2 CO—OH / CH 2 — CH> — CHo — CH NH 2 Lysine NH 2 CO—OH / CHo — CH> — CHo — CH 2 — CH NH, Hydroxy- and. of new material has been added. CAN SCIENCE EXPLAIN LIFE? INTRODUCTION The various forms of life which are encoun- tered in nature exhibit such a variety of appear- ances and such a profusion of. a 5 38207 6 Can Science Explain Life? sharp line of demarcation between living and non- living things. Although growth and reproduc- tion, in their broadest aspect, amount to nothing more than self-duplication, yet