Alanine is heavier with a ($\ce{-CH3}$) than glycine which has an ($\ce{-H}$). What makes them have different $\mathrm{p}K_\text{a}(\ce{-NH3+})$ $(\mathrm{p}K_\text{a}: \text{Ala}=9.69, \text{Gly}=9.60)$ but similar $\mathrm{p}K_\text{a}(\ce{-COOH})$ $(\mathrm{p}K_\text{a}=2.34)$ when the rest of the amino acid is similar? Why does changing a hydrogen for a methyl group affect the $\ce{-NH3+}$ but not the $\ce{-COOH}$?

Also there are three amino acids (glycine, leucine, aspartine) which have same $\mathrm{p}K_\text{a}(\ce{-NH3+})$ but different $\mathrm{p}K_\text{a}(\ce{-COOH})$.

Alanine is heavier with a ($\ce{-CH3}$) than glycine which has an ($\ce{-H}$). What makes them have different $\mathrm{p}K_\text{a}(\ce{-NH3+})$ $(\mathrm{p}K_\text{a}: \text{Ala}=9.69, \text{Gly}=9.60)$ but similar $\mathrm{p}K_\text{a}(\ce{-COOH})$ $(\mathrm{p}K_\text{a}=2.34)$ when the rest of the amino acid is similar? Why does changing a hydrogen for a methyl group affect the $\ce{-NH3+}$ but not the $\ce{-COOH}$?

Also there are three amino acids (glycine, leucine, aspartine) which have same $\mathrm{p}K_\text{a}(\ce{-NH3+})$ but different $\mathrm{p}K_\text{a}(\ce{-COOH})$.

Alanine is heavier with a ($\ce{CH_3}$) than glycine which has an ($\ce{H}$). What makes them have different $pK_{a}(\ce{NH_3})(pKa: Aly=9.69 , Gly=9.60)$ but similar $pK_{a}(\ce{COOH})(pKa=2.34) $ when the rest of the amino acid is similar? Why does changing a hydrogen for a methyl group affect the $\ce{NH_3}$ but not the $\ce{COOH}$?

Also there are three amino acids(Glycine,Leucine,Aspartine) which have same $pK_{a}(\ce{NH_3})$ but different $pK_a(COOH)$.

Alanine is heavier with a ($\ce{-CH3}$) than glycine which has an ($\ce{-H}$). What makes them have different $\mathrm{p}K_\text{a}(\ce{-NH3+})$ $(\mathrm{p}K_\text{a}: \text{Ala}=9.69, \text{Gly}=9.60)$ but similar $\mathrm{p}K_\text{a}(\ce{-COOH})$ $(\mathrm{p}K_\text{a}=2.34)$ when the rest of the amino acid is similar? Why does changing a hydrogen for a methyl group affect the $\ce{-NH3+}$ but not the $\ce{-COOH}$?

Also there are three amino acids  (glycine, leucine, aspartine) which have same $\mathrm{p}K_\text{a}(\ce{-NH3+})$ but different $\mathrm{p}K_\text{a}(\ce{-COOH})$.

Alanine is heavier with a ($\ce{CH_3}$) than glycine which has an ($\ce{H}$). What makes them have different $pK_{a}(\ce{NH_3})(pKa: Aly=9.69 , Gly=9.60)$ but similar $pK_{a}(\ce{COOH})(pKa=2.34) $ when the rest of the amino acid is similar? Why does changing a hydrogen for a methyl group affect the $\ce{NH_3}$ but not the $\ce{COOH}$?

Also there are three amino acids(Gly,Leu,Asp) which have same pKa(NH_3) but different pKa(COOH).

Alanine is heavier with a ($\ce{CH_3}$) than glycine which has an ($\ce{H}$). What makes them have different $pK_{a}(\ce{NH_3})(pKa: Aly=9.69 , Gly=9.60)$ but similar $pK_{a}(\ce{COOH})(pKa=2.34) $ when the rest of the amino acid is similar? Why does changing a hydrogen for a methyl group affect the $\ce{NH_3}$ but not the $\ce{COOH}$?

Also there are three amino acids(Glycine,Leucine,Aspartine) which have same $pK_{a}(\ce{NH_3})$ but different $pK_a(COOH)$.